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The Broken Social Promise

If you’re like me, the probability is that you were raised with the idea that if you did what you were told – and studied hard – then you would get a good job…and be happy.

I started to detect cracks in that proposition when I was very young.  The highest academic achiever in my first year high school class did as he was told, studied hard – qualified as a doctor…and then took his own life.  That, and many other inconsistencies during the ensuing decades convinced me that, as a life strategy, the ‘be good, study hard, get a good job, be happy’ idea was flawed at best – and an outright lie, at worst.

If we follow the trajectory of most of those who subscribed to this idea, what we really see are people who actually struggled to put themselves in a position where they got to work for others…for up to 50 years…on the understanding that they could then please themselves about what they did with what remained of their lives.

Of course, that all assumed that things went according to plan.  

It assumed that your ‘good’ job paid enough for you to accumulate enough to survive with dignity – much less to ‘please’ yourself. It assumed that you managed to avoid the substantial list of natural (and man-made) disasters that were generally regarded as ‘acts of god’ – a general description for the calamities that befall people for which no one is taking responsibility.  It assumed that you avoided life’s bastards – the bandits who prayed on the soft targets who were busily following the prescribed societal direction.  It assumed that you remained in good health in an environment that directly discriminated against good health.  It also assumed that you actually lived long enough to get your share of the social promise.

Most importantly, however, it required you to surrender your freedom for the greater part of your life in pursuit of ends for which there were no guarantees.

Let’s remember that these are the folks who got a ‘good’ job.  

Those who did not do well in an educational environment set up by the ‘haves’ often found themselves working in ‘minimum wage’ jobs that did not even provide the food, shelter and other necessities of a civilised and dignified existence.  These were the ‘have nots’ that were destined to become factory fodder for the ‘haves’.

Then there’s the sick, the aged, the minorities, the traumatised veterans and those who otherwise struggled to function within the societal framework established by the folks who own it.

Now, whether you subscribe to my view of how things work – or not – is not important…and nor is it the point of this post.  The important thing is to understand that, for so many people, the social promise was/is not delivering.

The next thing to determine is whether you’re one of them.

If you’re….

  • Getting older and find that, as life should be getting easier, it’s actually becoming much harder.
  • A parent of young children who is locked in a day-to-day struggle to make ends meet.
  • Concerned about the looming gap between the world’s population and its capacity to feed itself in the face of pollution, aquifer depletion, desertification, erosion, climate change and the other serious environmental threats confronting us.
  • A young adult wondering how you will ever achieve the ‘the great Australian (or other country’s) Dream’ of home ownership.
  • On a treadmill, working for people who don’t respect you or your abilities.
  • Approaching ‘retirement’ and an increasingly uncertain future.
  • Marginalised, disadvantaged or disenfranchised…or lacking any sense of control over your own life and its circumstances.
  • Convinced that the world is facing an imminent survival threat.
  • Tired of the growing hoard of bastards who are roaming through your pockets with a sense of entitlement.
  • Just someone who is seeking a more fulfilling life.

…then you’ve taken the first step toward a more satisfying life…simply by acknowledging your dissatisfaction with the status quo.

The good news is that there’s light at the end of the tunnel…and it’s not the train.

It’s called happiness…and it should be your highest priority.

In my next post, we’ll explore what happiness is…and then, in subsequent posts, we’ll get into how it’s possible to have more for less – with happiness as a consequence.



Welcome to

Let’s begin with a brief explanation of what the site is really about, how it came into being…and then I’ll talk about what it seeks to achieve.

Websites are like children in several respects…not the least of which that, if you have too many of them, they are subject to neglect.  That was certainly the case with me.  My Microponics site was only getting updated spasmodically and the home of the Urban Aquaponics Manual (long overdue for revision) was similarly neglected.  My old forum Aquaponics HQ (now Aquaponics Nation) had changed hands but I was still its principal contributor.

Suffice to say, I had stuff everywhere.  The other problem was that, since most of my content involved food production, my websites never fully represented the scope of my interests.

So, in early 2017, I decided to rationalise my various sites – and  my collection of domain names.  It was time to develop content in one place – and to conduct the discussions around my interests in another.  That’s it…just two websites.  And Facebook!  Like it or loathe it, everybody is there so I use it as a billboard to announce my latest mutterings.

In an attempt to lend some order to the process, I listed my various interests.  Long story short, a pattern (and life purpose) emerged and the Have More For Less discussion forum…a place where I can share and discuss ideas about self-reliance and simple living…was the outcome.  Over time, I plan to transition the content from my old sites to this one and the HMFL forum.

I’ve been blogging and self-publishing for over 13 years…and I like it.

While the HMFL platform is certainly fit for the purpose of discussion, it’s blogging capabilites leave much to be desired.  The other problem with discussion forums is that it appears that their owners should set a behavioural standard for the other participants.   If I have to behave on HMFL, then I need someplace that I can say what I want without having to tread the minefield of people’s feelings.  

This is that place.  

Note:  I’ll endeavour to identify content that is likely to offend so that it might be avoided…by those of gentle disposition, the politically correct…and my old mum.

In effect, the blog aspect of is a gateway.  It’s here that I’ll also introduce various ideas related to HMFL (and all of its aspects) with the idea that any ensuing discussion can take place back on the forum.  I’ll then post a link to my Facebook pages and groups for those who can’t fathom a universe outside of Facebook.


USDA-funded Commercial iAVs Trial – Notes on the Yield and Adjusted ‘ratio’.

The USDA-funded Commercial Trial conducted by Boone Mora happened on the heels of the iAVs research conducted by Dr Mark R McMurtry…and confirmed the commercial potential of the method.
iAVs NC Commercial Demo Project, USDA/Mora/Garrett, 1992-93; 
        —[ by total novices, under poor to fair conditions, very (too) LOW v:v ratio. ]
  • Total area 929 m2,  FT 200 m3, Tilapia yield 22,700 kg/yr (first ‘try’)
  • Hort. area (min.) 400 m2 total,  264 m2 net,   1,056 plants @ 4/m2
  • Fruit (mix Cucumber, Pepper, Tomato) : greater than 45,400 kg/yr   (45 MT)
  • 2016 estimated wholesale value $325k/yr ($350 m2/yr)
BUT Adjusting to the suggested baseline ratios
 i.e., v:v (1:2+),   v:a (1:6+),   (feed-fish):fruit (1:7+)
that 22.7k kg fish, (i.e.~30k kg feed, to Pmf 250g in <120 days 3x/yr or 350g <180 days 2x/yr)
  is enough TAN and excrement to grow 
  • 8,000 to 10,000 indeterminate tomato plants (on 12 mo cycle)  (9,000 applied below)
    • (or 3 times that if a 4-month crop interval 3x/yr, and/or equivalent crops)

2016 estimated  US ‘organic’ bulk wholesale valuations:

  • tilapia (live): 22.7k kg x $3.30/kg = $75k/yr 
  • No. 1 ‘organic’ tomato: 170k kg x $5.5/kg = $935k/yr
  • No. 2 ‘organic’ tomato: 40k kg x $3.5/kg = $140k/yr
  • Total above (without intercrops etc) = $1,150k ($300/m2/yr)

At 2015 Philly Terminal wholesale prices. 

  • Organic No 1 @ $6.90/kg -10% = $6.20/kg  (> $1,056k)
  • Organic No 2 @ $4.80/kg – 10% = $4.35/kg  (> $174k)
  • Total w/ fish $1,305k or $343/m2/yr)
  •        w/ very hi-tech GH with intercrops from $450 to 500/m2/yr) 
  • …   + 30-50% or more when retailed, direct-marketed, NTM value-added processing


Fish Stocking and Feeding (place holder)

This topic would be several long chapters in a book, or an entire book in itself, which I am NOT writing – ever.  It is therefore strongly suggested that one study the requirements, behaviours and life-cycle factors of the species you are attempting to grow from responsible sources.

Far TOO many variables to even begin to suggest a ‘standard’ or ‘baseline’.

FACTORS wrt stocked density (collective biomass per unit volume, not the number of individuals)

  • Species cultured
  • Temperature
  • DO level (diurnal low)
  • pH, EC, etc.
  • Targeted harvest size
    •  (daily ration rate as % of body weight declines and FCR increases with increasing individual size attained in most if not all species, sometimes dramatically, regardless of other parameters)
  • Static vs dynamic stocking management
  • Feed Composition
  • Feed Ration (rate) and diurnal regime
  • Amount of biofiter volume
  • Crop(s) and mean current growth (uptake) rate(s)

Factors wrt feed

  • Species cultured
  • Mean individual size (age)  – assuming similar cohorts
  • Feed Quality (including elemental composition)
  • prevailing water quality factors
  • Daily feed regiment


When we add fish feed to the iAVs, we’re actually feeding the entire so-called ‘system’ … the fish, plants and the beneficial micro-organisms that inhabit a mature stable ecosystem.

Mark…..I need anything useful/relevant that you can remember about the feed.

Both P’86 and Ratio Studies used Purina Mills 5140 floating pelletized Catfish Chow, labeled as 32% protein without the ‘normal’ addition of mineral and vitamin supplements.  – apparently no longer made/sold  (at the time there was no such thing as a tilapia chow in the US and I know less than nothing about what may have been developed since).  I do not have an ingredient list.

Feed composition

(click image to enlarge)

Residual levels (plant tissue and media accumulation) of Sulphur, Copper and Zinc were determined to be high, no toxicity symptoms were observed.  Obviously, the fish didn’t need/use these in the proportions provided. Potassium began moderately limited (plant tissue) at the highest ratio (largest filter volume).  Boron was relatively low for one particular tomato variety grown in the higher (1:1.5 and 1:2.25)  ratios.

NOTES on Feed Rates in iAVs Ratio Study: Mean feed ration per day in the iAVs ratio studies (over 370 days) was 133 grams/cubic meter/day.  Range was 80 to 360 g/m3/d.  Inputs were held constant across all v:v ratios.  At a v:v ratio of 1:2 a slightly greater feed rate is possible.  These studies were conducted with ‘male’ hybrid tilapia.  Young fish consume a higher amount of feed relative to their body weight than do older/larger fish.  Mean daily feed rate as % Pmi (individual weight) was 9% @ 15 gram size, 2% @ 250 g, 1% at 500 g, 0.6% at 750 gram.  Initial stocking was approx. 80 ea. @ 15 gram fish per cubic meter.  They reached Pmi of 265 grams in approx. 115 days.  At which point, the number of stocked individuals per tank was reduced (sequentially harvesting larger specimens at approx. 3 month intervals).  FCR declines with increasing Pmi in most if not all species. Tilapia are especially noted for this tendency above Pmi of 250 g.    Initial FCR was 1:1.1.  At 265 g, FCR was 1: 1.5.  At 500 g, FCR was approx. 1:2.0.  At 750 g, FCR >1:2.5.  I was likely overfeeding albeit all feed was being consumed within 5± minutes.   The aforementioned 360 g/m3/d feed input rate was not sustainable (advisable) at the biofilter v:v ratios used.  BTW, these fish were severely stressed by being sedated every 30 days in order to monitor biomass increase rates.  Even though declining growth rates and feed conversion is typical for tilapia, an unknown portion of the documented declines may be attributed to this repeated stress.


Obligatory rant:  Never ‘just’ take anyone’s word or pronouncements as being valid because of their alleged relative ‘expertise’ without also confirming/checking other responsible sources of information. Especially do not blindly accept input from someone who hasn’t actually raised your species at the density, size and with method (feed, filter(s), etc.) that you are employing.  And ‘just’ because someone may be charging a fee for dispensing ‘sage’ advice in NO way implies that the content (esp. in your context) will be in anyway accurate/reasoned/sound.  There are many thousands of self-inflated know-it-all blowhards ‘out there’ attempting/competing to ‘suck you in’ to their baseless fantasy delusions.  Caveat emptor.

Nature Bats Last

“Nature Bats Last.  Our days are numbered.  Passionately pursue a life of excellence.”

While I wish I’d said that because it sums up my personal view of the world.

As it turns out, it actually belongs to Guy McPherson (Professor Emeritus – University of Arizona) – an outspoken (albeit very interesting) commentator on the future of human civilisation.

Regardless of its origin, or circumstances, it’s a prescription that would be useful for all of us.





SAND particle size distribution recommendation and Costs – AGAIN!

SAND particle size distribution recommendation – for the LAST time

I know what I know, did what I did, documented it … and this is what (ALL) I can speak to from authority/experience (recommend).

The sand that I used performed spectacularly well in every aspect/way – IMO – I can’t image a greater efficacy.  I’m not saying that some other fractionation will not ‘work’ … however defined/determined/felt  … but how well is good enough for you is for you the decide?

I used sharp (crushed) quartz (SiO2), which was chemically inert (does not effect pH) in the following grain size distribution (summarized):

  • 30% by volume in the size range between 1 to 2 mm  (+/- 2%)
  • 40% by volume in the size range of 0.5 to 1 mm  (+/- 2%)
  • 25% by volume in the size range of 0.25 to 0.5 mm  (+/- 2%)
  • less than 0.25 mm (combined, including silt) at a maximum of 8% by volume (less is better).

FYI, with this particle size distribution I experienced lateral water movement in pristine furrows (very first irrigation) of  approximately 4 to 5 meters in length – no problem.   For furrows of 8 to 10 meters in length I laid a 4-6″ wide strip of 5 mil clear polyethylene film in the furrow and cut closely spaced slits/holes in that film to help the water/wastes reach the end, but only for approximately the first week.  After that, the biofilms and detritus layer had developed to the point where I removed the temporary perforated film (leaving any detritus on the actual film in the furrow).  With or without an initial ‘film assist’, I observed virtually no erosion of sloughing of the ridges from day one or at any other point in time in any ‘system’.  Believe it or not.  Everything I say is intended for YOUR benefit, not mine.

For further discussion on sand, please use the search function (upper right) to access previous discussions – including as it compares to gravel.


And while on the sand topic (AGAIN) … I keep hearing complaints about it being so hard to find (in the US that’s BS) and also that is so damn expensive (also BS).  In the US virtually anywhere, sand, pea gravel and 3/4″ gravel are basically the same price by volume and/or by weight, whether from a quarry or in bags at your local big-box store.  Price varies by location and volume ordered, typically from $20 to $40 per ton (as low as $11yd3 in upper Midwest States).

In fact, for our US friends, it’s as close as your nearest Home Depot or Lowe’s. A company called Quikrete supplies both retailers with a diverse range of aggregates…including graded sands in many types and sizes…and for all manner of purposes. 

Examples: ALL Purpose Sand Product #1152….  AND   Commercial Grade Sand options. (click links)

For example,  in the Quikrete product line: product # 1961 is 30-70 mesh or 0.2 to 0.6mm), #1962 (20-50 mesh or  0.3 to 0.8 mm) and #1963 (12-30 mesh, or 0.6 to 1.7 mm).  With these particle size distributions, one might get away with using all as #1963, but personally, for every 10 bags, I’d make 3 of them #1962 to increase SSA, improve moisture retention and also improve lateral water flow along the furrows until such time as a detritus layer is established.

Bag prices (50 lbs or 22.7 kg) range from $4 to $8 per bag at retail outlets everywhere – varies by location – but bags are the most expensive route possible.   One cubic yard = 52 bags of 50# at 2,600 lb/yd3 for dry sand

1 cubic yard of dry sand weights from 1.3 to 1.35 ton, so per cubic yard quarry tonnage rates range from $26 to $54/ yd3, or $34 to $71/ m3.   Bulk bags in the midwest states (e.g. Oklahoma): 3000# bulk-bag of 20-40 US sieve #24 filter sand = $206 delivered to OKC (from Wisconsin, March ’17)).  At 2600#/yd3 = 1.15 yd3 or 0.88 m3. for  $179/yd3 or $234/m3. 

Here in Montana, bags (sand, pea gravel, etc) at Lowe’s (et al) are $4.25 /50#. (in bags you’re paying 3 to 4 times as much by volume than in bulk)   Local quarry prices range $35 to $45/cubic yard for single units of washed graded sand or $30 to $35/cubic yard in 10-yard truck loads (plus $0.25 to $0.30 per mile)  I have a choice of at least 3 quarries, 2 concrete batch plants and a cinder-block plant just within 60 miles in one direction – each with multiple grades (size distributions) to choose from or mix and match).  In other words I can have 10 yards delivered (enough for 30 square yard of biofilter for under $500  – all day long from multiple sources. (<$1.85 ft2, <$20/m2).  Yes, it cost much more in bags …  but still damn CHEAP compare to clay ball crap.

Compare sand prices to Hydroton at Walmart (today) for $86 / 50 liter = $1,720 m3 ($1,338/yd3)  –  you order and go pick it up.  – or compare with Gyco branded Hydro-Clay, at $27 per 50 liter bag (online) plus shipping (one bag at $59.72 UPS ground to me) which for 8 bags (most they would calculate shipping on)  = $659.36/ 400 liter  = $1,650 m3

To summarize Basically, (in the US) gravel, pea gravel and sand are nearly the same price whether by the cubic yard, ton, or in bags,  Varies by location and volume purchased.   Cost ranges from $20 to $40/ton (bulk) or $4 to $8 /50# bag (as low as $11 cu yd in Michigan or Wisconsin)

Delivered quarry sand at $50/yd3 is 25 times LESS (+/- 4%) than expanded clay pebbles (which is a vastly inferior  media relative to sand in several aspects and it also degrades (breaks down) over time (sand does not degrade).

In iAVS, the sand does it all  = 1) mechanical filtration (99+% particulate removal) , 2) exponentially superior Nitrification substrate than ‘alternatives’, 3) Oxygen rich ‘home’ for biofilms and soil microbial community including robust rhizosphere, and 4) excellent, aerated anchor for vascular plant roots. That’s 4 critical (key) functions all in one package, at 4% of the cost of a significantly inferior ‘alternative’.  What’s not to love (complain about)?

I can’t speak for Gary but I am DONE with the entire sand subject.  If sand is felt to be too difficult to source and/or deemed to be too expensive for what it can do for you, then you would probably not be successful in maintaining a functional iAVs or any other AP so-called ‘system’  – IMO.



Effect of pH on plant assimilation of elements

I can’t stress strongly enough the importance of pH on biofilter performance and on plant growth (yield).

The recommended pH for iAVs (water) is 6.4 +/- 0.4.    pH will not only influence nutrient availability for the plants but also influences microbial metabolism (activity, efficiency and even community/species composition).  Nitrification is most efficient at pH 7.0.  In iAVs, there is such a vast surface area available for biofilms that more than adequate nitrification occurs at even as low as pH 5.0 (at least over intervals of several weeks).  The toxicity of True Free Ammonia for fresh water fish rises above pH 7.0 and goes exponentially more toxic above pH 8.0.  In other words, TAN is far more toxic at higher pH and than at lower pH.

Effect of pH on plant assimilation of elements, varies by soil type (and/or if soilless).

Hydroponic nutrient solutions are NOT organic – repeat NOT and never can/will be – so the above chart applies more in hydroponics (and likely DWC) than does the ‘organic soil’ chart below.

An iAVs biofilter prior to the inclusion of detritus/organics would be considered as mineral.  With the addition of organic solids (detritus) and with a developed soil microbial community, the biofilter becomes (is) ‘organic’ – aka includes Carbon-based biomolecules – (except for the ammoniacal Nitrogen fraction (TAN)).   However, TAN is not the only N source in iAVs.  Nitrogen is also sourced from amines, amino and nucleic acids (proteins), chlorophyl, peptides, some enzymes (hydrolases), ureides, et al. – each (with rare exception) being made plant available via microbial transformations (often  in a sequence involving multiple microbe species, as too with most other elements when sourced from complex organic biomolecules).

IMO, so-called ‘aquaponicists’ need to loose their apparent ‘fixation’ on (obsession with) Nitrification (‘seriously’) and start to include active consideration of the availability of ALL the plant essential elements.

NOTE:  Calcium toxicity rarely occurs. HOWEVER, high levels of Calcium can compete with (inhibit) both Magnesium and Potassium (and possibly Phosphorus) uptake by plants, resulting in assimilation deficiencies of Mg and K regardless of how much of these elements are in the media/solution.  In animals (vertebrates), excess Ca is antagonistic with Phosphorus metabolism.

Additional Note:  I’ve seen several submitted sand composition analysis recently indicating a percentage (1 to 2% by volume range ) of Calcium oxide (CaO).  This compound is highly water soluble and extremely basic (WILL strongly raise pH in a proverbial heart-beat).  I suggest avoiding media that includes CaO as well as similarly significant levels of Calcium carbonate (CaCO3) as well as Ca(OH)2 and/or  CaO2.

Charts sourced from “Knott’s Handbook for Vegetable Growers, 5th Edition”, an Industry Standard reference for many decades.

PDF version  KnottsHandbook2012

Hardcopy version available on Amazon

Feed and feeding notes:

There seems to be some ‘confusion’ about feed rates and I believe we’ve mentioned this far more than once in some blog posts and/or comments (both feed inputs and composition definitely covered in publications).  Rather than trying to find that or asking you to do so, I’m copying below some more recent responses to feed related questions.  
Do note that all this is strictly in regard to Tilapia with a balanced commercial feed (in my case of a known elemental composition).  I highly encourage others who are serious about plant production to have their fish feed analyzed (by a qualified lab) for the plant essential elements (yes, it will have a cost, what doesn’t? – except my efforts and time that is ! – to date).
If you have the option, feeds ‘fortified’ with mineral and vitamin supplement ‘packs’ are not necessary.  IMO, knowing what the amount of plant nutrients are in a particular feed will be useful information for you to have (and report).  If you have your’s tested, report the results to us and I/we will provide feedback.
Note: Anyone growing goldfish or other carps, perch, bluegill etc. should also know (IMO) what their feed composition is and I can offer ZERO suggestions as to what the appropriate feed rates (or temps, DO, etc) are at any size or density for any species except tilapia.  Also, if you have some prior experience with gravel or clay-pebble media, you will find being able to feed at a much greater rate when using sand as the filter media.
Response to Questions
RE: report of ‘slow’ plant development with indications of nutrient stress
If I’m understanding you correctly:   ‘wastes’ from 80 grams/day distributed over 30 m2 = 2.67 g/m2/day … which is ‘basically nothing’ – aka, no where near enough nutrient to support vigorous plant development
In the ratio studies (all-male Tilapia):
Feed given over the first 31 days starting with N= 80/m3, 15 g fingerlings  (includes 1 week at very low rate at start-up before ‘cycled’) = 3.43 kg/m3 (per tank, 31 days)
At v:v 1:2,  aka v:a 1:6   =  572 g/m2 (filter) or 18.44 g/m2/day (first 31 day average)
I also looked up the feed input rate data over the first 103 days.
  • First week input rate at 4.5% of biomass/day tapering off to 2.1%/day (last week avg.)
  • Total feed (mean) per individual = 257 g
  • Input rate as % of Pm (day 7)= 9.7%/day
  • Input rate as % of Pmf (day 103) = 1.8%/day…BTW:  “P” = individual, “m” = mass (weight), “i” – initial, “f” = final

The one-year feed input rate averaged 133 g/m3/day….which at v:a 1:6 = 22.17 g/m2/d. 

  • 2/3rds of that time was with fish larger than 300g (reduced feed as % of biomass/day and w/ lower FCR than smaller tilapia)…BTW: feed rate %/size and FCR are NOT linear functions
  • also included a 40+ day interval without any plants (intentional), then another month trying to raise pH again (with a reduced feed rate)
SO … I ‘feel’ that approx. 150 g/m3/day long-term average is a viable target (perhaps more w/ continuous/vigorous fruiting plant production).
At v:v 1:2, then v:a= 1:6 , so feed rate (‘wastes’ from) per m2 of filter in the 25 to 30 g/day range as a long term average (until determined either excessive/insufficient).
SO, if you can’t get the stocked fish to consume enough feed to sufficiently fertilize the entire biofilter area you have available, then temporarily reduce the portion of filter being irrigated/fertilized until they will eat enough to support more plant growth.  This can be accomplished by temporarily blocking off the furrows (length of) to limit the area receiving nutrient and just grow plants (initially) in that section until you are able to feed at a higher rate and increase active filter/plant area.
RE: Another response to similar question 
My one-year feed input rate averaged 133 g/m3/day (all-male tilapia)
2/3rds of that time was with fish larger than ~250g (reduced % of biomass/day and w/ lower FCR with increasing size)
also included 40+ days without any plants, then another month trying to raise pH again (reduced feed rate)
SO … I ‘feel’ that approx. 150 g/m3/day long-term average is a viable target (perhaps more w/ continuous/vigorous plant production)
At v:v 1:2, then v:a= 1:6 , so feed rate/m2 of filter in the 25 to 30 g/day range (until determined either excessive/insufficient). During a system start-up )with small fish and young plants) one can feed as much as the fish will eat twice a day and the plants should be okay (was for me) with the feed input increasing as both the fish and plants grow.  I believe that my initial feed rate during the first start-up ( still ‘cycling’, microbial populations just starting to develop) was 40 g/m3/day (at v:v 1:2 = 6.7 g/m2/day and was at 120 g/m3/d (20 g/m2/d) or more within a couple weeks.
What is the optimum water:sand ration? 1:2.4 or 1:1.5?
Depends on several factors, but over the long-run, the amount of feed input determines the amount of fish ‘waste’ generated, and the amount of ‘waste’ being accommodated (on average, over time, many months to a year) would dictate the appropriate  filter volume.  More feed = more ‘waste’ = more filter surface and more soil biology to process.
We have been suggesting v:v =1:2 (or v:a 1:6) for first time adopters as suitable for from 80 to 100 tilapia  per cubic meter grown from 15 g to 250+/- gram in 3 to 4 months assuming they are feed a balanced ration fed all they will eat twice a day. Once they’ve attained 250 g (approximately) then the ‘standing biomass’ should be reduced (by culling or increasing volume(s)).
Since I’m mainly interested in the ‘wastes’ (more than the fish production), one could also have greater fish numbers and feed them less intensively (grow more slowly) or even fewer fish and fed very aggressively assuming that water quality remains ‘good’ (allows)
What is the fish density? by weight or by number? assuming 15 grams fingerlings?
In the ratio study. I had N= 80 m-3 at Pmi =15 g  – they did ‘fine’ across all the v:v ratios from 1:0.67 to 1:2.25
At v:v 1:2, one should be able to do well at N=100 m-3 (reduce N when attaining 250 +/- 50 g  average size).
Growth rate and FCR was slightly better in the higher ratios due to ‘cleaner’ water. Plant yield per plant and per area was better at the lower ratios but total plant yield per filter (not area) and per gram of feed input and per fish growth/increase was greater at the higher ratios.  The combined yields per unit feed input was found to be between the 1:1.5 and 1:2.25 ratios (under those prevailing conditions), So, I’ve suggested 1:2 for beginners for both simplicity and leaning toward the larger biofilter capacity to error on the side of caution (for the fish).  Also note that this was with (for) indeterminate tomato and cucumber and not for leaf crops, legumes and/or cole (Brassica) family.  
There is no magic one-size-fits-all number for feeding rate.  All feeds vary in composition, All fish species and growth phases have different requirements (upper and lower limits and an unknowable optimal rate on any given day), All sand, water qualities and locations will be at least somewhat different – overall and as time/seasons progress.  All plant species and phases of their growth will have somewhat different nutrient uptake rates (by amount and element – each and every day).
The fish will indicate through their feeding behavior if they are hungry (when full).  The plants will ‘tell you’ by their growth rate and any foliar symptoms that might develop if they are getting enough nutrient or not.
As a ‘system’ matures (elements accumulate), feed (nutrient) input each and every day is not critical from the plant’s ‘perspective’..  Longer term (monthly) feed rate, aka ‘waste’ generation should be approximately balanced with the prevailing average plant nutrient uptake.  As the ‘soil’ develops, as with an in-ground garden, there is no need to add fertilizers to the media (plants) each and every day (or even week).  Sure, the fish will want to be fed every day – but provide enough feed ‘run through’ enough fish to supply the nutrient demands of the plants (number, species) you are growing.  Not more (long term), not less (long term).  Balance.
There are dozens of variables ‘at play’- every day,  changing one aspect/parameter WILL influence everything else eventually,  This is the ‘nature’ of an (every) integrated “SYSTEM”. Know what is actual happening in your system (pH, temp, DO, feed input/quality, FCR, etc.) , Observe what is happening carefully and often.  Observe, assess, adjust, observe, assess adjust, repeat, repeat repeatedly.
REMINDER:  Plant nutrition is STRONGLY influenced by pH. … with 6.4 to 6.5 generally ideal for most species and elements.  I suggest the outer limits for good plant nutrition/growth to be pH 5.8 on low (acid) side and 6.8 on the high side.  Most AP seem to claim/prefer to exceed pH 7.0.  This is NOT ‘good’ (recommended).  Facts are facts and unsubstantiated opinions aren’t.  Believe it or not.  Totally your choice.  Every and ALL content I/we provide is exclusively intended to be to your direct benefit.  Argument (in the absence of evidence) is not appreciated.
And, as another reminder, iAVs is 90+% about plants.  Fish growth is a means to an end.  It’s the metabolic ‘waste’ products (and microbial ‘processing’ thereof) from the fish growth (feed) where the value  resides (both economic and nutritional).  If you are merely interested in fish production and with tinkering with equipment, plumbing and sundry gadgets&gizmos then (IMO) stick to standard recirculatory aquaculture practices (not so-called ‘aquaponics’ – whatever it is you ‘think’ that is/involves).  Seriously !

How long is a piece of string?

We’re frequently asked to provide ‘simple’ answers to complex questions.

When we speak about  ‘complex’ questions, we’re referring to those that require consideration of several factors in the formulation of answers.  Common examples include:

  • How much aeration do I need?
  • What size pump should I buy?
  • How many fish can I stock in my system?

The fact is that many factors will need to be considered when formulating a response that is appropriate to your circumstances…so there is no simple answer to any of these questions.  

Our only possible response, in the absence of much more circumstantial information is one of…Enough.  Enough aeration to provide oxygen to the fish, plants and microorganisms that facilitate iAVs. Enough pumping capacity to manage water quality and to irrigate the plants.  Enough fish to nourish the plants.

To respond to these (and many other similar) questions in any really useful way would require the following information

Having all of this information to hand is one solution to simple questions in complex situations…but is it the best one?

So … to questions such as with this example, I recommend that the petitioner investigate (learn) what the applicable factors influencing your decision are, to accurately assess your personal circumstance/situation in context, and then act accordingly to that need.  I cannot know the many details of your unique situation and I have no personal obligation to learn/list them and/or pry-out the specific influential criteria in your situation and then do the necessary calculations for anyone.  Not to mention, that just ‘giving’ an answer (guaranteed to be inappropriate), does not allow someone to learn what it is that they need to know.
 If you have a need to know something, its up to you to learn what the relevant factors are in making an informed decision that will be appropriate to addressing your need.  Presuming literacy and numeracy, ‘Google’ is your friend to learn what you need to know and then know what to do to address meeting your goal.  I cannot and should not be expected to do that for you (anyone).
Your mind is your survival tool.  Employ it purposefully.  The only person responsible for your every action and therefore outcome is you.  Learn > Act > Grow  !!    Learn more > Act from understanding > Grow further !!     Repeat, repeat, repeatedly.
In other words, don’t ask me what you need – find out for yourself and then you’ll know

The "Right" Sand, one more time …







When we used the term “sand” we are referring to sand-sized grains (0.25 to 2.0 mm) composed of the mineral Silicon dioxide {SiO2), aka silica crystals, as being typical found in (sourced from) granite and quartz rock.

Criteria 1:

That the sand used “drains well” … and nearly completely.  “Drains well” basically means going from a fully saturated (completely flooded) condition to when observable (unrestricted) drainage ceases within approximately 10 to 20 minutes from a 1/3 meter deep sand profile – once input pumping has stopped.

Drainage rate (aka hydraulic conductivity) is dominantly influenced by the average particle size but also by the specific particle size distributions (proportions).  Smaller particles (the more of them there are and the smaller they are on average) will produce increased drainage times (slow the drainage rate).  Also, the smaller the average particle size is the more water will be retained (not freely drain),  which would then occupy more of the pore space (blocking O2 and therefore inhibit aerobic organisms which includes plant roots), especially in the lower portion of the depth profile.

Criteria 2:

That the sand is chemically inert, meaning that it does not significantly change the pH of water coming into contact with it.

In other words, it does not contain water soluble compounds (material), such as Calcium carbonate (CaCO3) or Calcium Oxide (CaO), as two common examples.

With a  source water at pH 7 or below, a pH change of the water with each flooding/return of 0.0 would be ideal,  but pH +0.1 to +0.3 under initial conditions may be acceptable.  Remember than pH is a logarithmic scale, a change of one pH unit (+/-1.0) corresponds to a ten-fold change in the Hydrogen ion concentration.

NOTE: Use of source water above pH 7 is NOT advised.  If your ground/source water is, for example, pH 8, then lower the pH (with an acid, i.e Phosphoric or Sulphuric) to below pH 7, BEFORE adding it to the system.  In such a case, a separate (independent) storage tank expressly for this purpose is advised.  Harvesting and use of rainwater is strongly recommended for virtually all locations.

Criteria 3:

That the sand contains NO contaminants such as heavy metals, radio-nucleotides, water-soluble salt(s), plant pathogens, or man-made chemical pollutants to include all pharmaceuticals.

Example metals and nucleotides include:  Antimony, Arsenic, Cadmium, Cesium, Chromium, Lead, Mercury, Palladium, Platinum, Plutonium, Radium, Thorium, and Uranium isotopes.

These elements are found only EXTREMELY rarely (not a legitimate concern) in manufactured sand (crushed from ‘virgin’ granite or quartz) but MAY be found in certain natural sand deposits, particularly along river banks and lakes downstream or downwind of human/industrial activities.

Beach sand is almost always dominantly Calcium carbonate and therefor is not suitable (exception being volcanic glasses).  Limestone is obviously not viable and neither are most sandstones and other sedimentary composites, unless exceptionally ‘pure’ (99% SiO2).

That’s it, folks:  1) drains well, 2) chemically inert, and 3) no toxic contaminates.


A final note of CAUTION:  Do NOT accept any vendor’s claim of anything as being true (factual).  Always test the sand source being considered (drainage rate and pH effects) for yourself.  Minimize the risk of potential contaminants by sourcing ‘virgin’ crushed stone.


Further information can be found at:

Sand Selection Guide


Sand versus Gravel as a Biofilter Media

Sand Bio-filter Construction and Operation – Part 1





Why Does iAVs Use Sand?

The use of sand for use in water filtration pre-dates recorded history. Sand was ‘understood’ to be a highly effective means of purifying water by the Babylonians, ancient Africans, Chinese, Egyptians, Israelis, Native Americans etc … albeit that they did not know ‘exactly’ how or why it did so (microscopic particles and microorganisms being totally unknown to them). They ‘just knew’ from direct experience/evidence that it did ‘work’ and worked well with little to no effort.  That’s truly all that they actually needed to know … and in reality, that’s basically all that anyone (you) really needs to understand … it just works … every where and every time.

This is FAR from a new concept or novel technology and as such not alleged (by me) to be an invention in any way, shape or form.  Sand filters remain the preferred filtration media, still in continuous use today, by for example professional aquarium managers such as at SeaWorld and Epcot Center.

Sand filtration is basically ‘fool proof’, works every time, automatically, effortlessly and effectively.  Sand (Silicon dioxide e.g. quartz) does not break down, wear out or need replacing (within reason) and is basically infinitely recyclable.  Even if/when it might eventually become ‘overloaded’ with organic ‘wastes’ it can easily be cleaned, flushed and reused repeatedly. And if that should ever present ‘too much hassle’ for someone, it can always be sold (as a value added product) as a soil amendment to organic gardeners, farmers in regions with heavy clay soils, golf courses and likely put to other uses.

When (medium to medium-coarse) inert sand is employed to filter ‘waste’s from aquaculture, the sand surface physically strains the suspended solid ‘waste’ fraction (particles, including microscopic) from the water, leaving it at/near the surface exposed to Oxygen and rapid decomposition.  Sand has an extremely high specific surface area (composite surface area by volume) for soil microbes to attach and/or inhabit,  A well-drained sand is approximately one-third pore space (atmosphere) by volume.  This means that a non-saturated (drained) sand has ample atmosphere (21% Oxygen or 210,000 ppm) to support vigorous aerobic soil microbial communities.

Products of the initial ‘waste’ decomposition occurring at/near the surface migrates(moves) down into the subsurface sand with each subsequent irrigation event, where these compounds are sequentially ‘processed’ (metabolized) by multiple species of soil microorganisms.  A diverse soil ecosystem develops naturally and autonomously. which progressively, biologically transforms the fish ‘waste’ products (both the solid fractions and solutes) into nutrient forms that vascular plants grown in the sand will assimilate.   Plants grown in this organic-rich sand (soil) perform the function of filter cleaners by extracting their nutrient requirements from the sandy soil and thereby limiting/preventing toxic accumulations.

The sand (physical substrate) + Carbon- based biomolecules (organic fish ‘wastes’) + soil microbes + water and Oxygen SOIL.

In Summary, the use of sand as an extremely effective and highly practical filtration media is not Not NOT a ‘new’ or in anyway a novel technology. It has been consistently proven effective for at least 10 millennia (probably far longer) and there is absolutely nothing about sand or sand filters in the digital age that can/will ever change that in the slightest.  Similarly, “soil” (mineral + ‘organics’ + aerobic microbial life) is well understood to support vigorous plant growth.  Removing aquaculture ‘wastes’ from water permits the return of clean water for reuse.  Providing organic-rich fish ‘wastes’ along with abundant Oxygen and water to a mineral substrate (sand) will support rapid plant growth with high yields.  That is what iAVs does (is).

PS: Neither gravel nor expanded clay pebbles has ever been known/shown to be an effective filtration or water purification media. … not in pre-history (assumed), over recorded history, and certainly not over the past 27 years of fraudulent nonsense disseminated at the speed of light by willfully gullible modern-primatives.


iAVs is not……

Most of the articles on this site endeavour to enlighten readers as to what iAVs is.  We thought it would be interesting to canvass all of the things that it is not.

  • It’s not hydroponics – it has more in common with organic gardening than hydroponics.
  • It’s not a miracle – it’s roots are firmly based in science rather than magick.
  • It’s not going to feed the world – most of the world’s calories come from grains – but it will expand the nutritional base of anybody who uses it.
  • It’s not a religion – it’s biology.
  • It’s not going to save California from its water woes – although it is the most water-efficient food production method anywhere.
  • It’s not based on plastic or pumps.
  • It’s not going to enrich Dow Chemical or other polluters – because it doesn’t require miles of PVC pipe or mountains of Styrofoam.
  • It’s not basic flood and drain – it actually works.
  • It’s not new – although it spawned everything that subsequently became known as aquaponics.

Most of all…’s not aquaponics –  it’s much more.


iAVs – Easy!

We keep saying that iAVs is simple to understand and easy to build and operate.

Here’s iAVs in  5 steps (images not necessarily to scale).

Click on images to enlarge

Simple plot 1

Simple plot 2

Simple plot 3

Simple plot 4

Simple plot 5

Proportions depending on loading (fish density and feed rates),

Simple doesn’t have to mean dull or inflexible….particularly where iAVs is concerned.

Various iAVs layouts


Do Sand Beds Need Cleaning?

One of the questions that crops up from time to time is…..”Do sand beds need cleaning?”

No form of so-called ‘aquaponics’ is a perpetual motion machine.  Every ‘system’ type requires periodic maintenance – and iAVs is no exception to the rule.

Everything that one inputs into a ”system’ remains in that ‘system’ until it is removed in the form of fish and plant tissues – or mechanically by the system operator.

The longevity of a iAVs biofilter will be influenced by many factors.  Such factors include:

  • The filter media type, extent (relative scale), effectiveness/capacity.
  • The stocking density and age (size) of the fish.
  • The feed input rate and its elemental composition.
  • The feed conversion ratio realized (to a lesser degree the particular fish species cultured).
  • The amount and type of plants and the predominant growth phase of your cropping schedule.
  • The microbial populations (range/scope and density/activity).
  • The availability of molecular Oxygen for aerobic metabolism.
  • Other parameters such as temperatures, pH, alkalinity, EC, CEC.

One of the many benefits of sand as biofilters is that sand can be repeatedly cleaned and reused. 

Suggested methods to prolong useful cycle ‘life’ in a sand biofilter:

  1. Stock the system with fish sufficient to meet the nutritional needs of the plants.  Remember, iAVs is a horticulture system where fish production is the means to an end rather than the end itself.
  2. Do not over feed the fish.  Ideally, ALL the feed should pass through the digestion tracts of the fish.
  3. Highly efficient mechanical filtration (related to particle size) of the solid fraction with ‘wastes’ exposed to atmospheric O2 concentrations and hydration such as at the surface of (and in the upper strata) of a reciprocating sand biofilter.
  4. Maintain a full compliment of beneficial soil organisms to effectively bio-process all ‘wastes’ into plant available nutrient forms.
  5. Maintain plants at relatively high density across the entire biofilter surface and with most plants in the log growth phase. Try to not have all plants either very young or very mature.
  6. Employ a feed composition that is balanced for the fish species but also for plants’ assimilation requirements (e.g., not excessive in Sulphur or any metals – which at least some commercial rations are).  
  7. Grow plant species with ‘high’ nutrient demand requirements in proportion to feed input composition (e.g., not mostly lettuce and other leaf crops).

Some aspects to monitor for clues when you will need to change/clean your sand of unwanted accumulations:

  • Monitor percolation/drainage times through the vertical column of the biofilter (other than at the immediate surface/in the furrows) – suggest establishing a baseline interval between initial irrigation on cycle to the initiation of return drainage in the ‘fresh’ biofilter – compare this duration at intervals as time progresses.
  • Investigate bottom layer of biofilter every 6 months or so for signs of refractory solids.
  • Sight, periodically evaluate coloration and turbidity of the drainage water.
  • Smell, when investigating lower volume of biofilter, attempt to detect any slight odor , especially Hydrogen Sulfide (rotten egg smell).

Some thoughts on cleaning sand of accumulated/ excess material

  • Sand can be reused indefinitely.
  • Have a back-up/contingency plan e.g., replacement sand and or additional/alternative biofilter(s) in advance of need.
  • In septic and waste water treatment “slow sand filter” systems,  eventual sand rejuvenation is typically limited to the first few millimetres of the surface. The intervals between ‘cleanings’ are measured in years (1-5), but such ‘systems’ do not benefit from ongoing mineral assimilation provided by plant production.
  • Sand can be mechanically agitated and screened (even successively if required)  to remove accumulations of all particles smaller than the recommended grain size.
  • The more one can spread out a sand volume into a greater surface area (shallower depth), the easier/faster cleaning via any method will become.
  • option; remove sand from biofilter, spread out onto well drained ground and allow rain and sun to wash it for you (over time), stir/mix occasionally – the necessary time duration will depend on your climate/precipitation patterns.
  • If climate/weather is not conducive, construct a sand washing unit – visit sand quarries to observe/learn their methods.
  • To loosen ‘problem’ (resistant)  coating/films, place on moving conveyor passing thru dilute Hydrogen peroxide solution bath/shower (recycle solution).  Rinse with freshwater before returning to use as a media.
  • Decouple biofilter drainage return from the grow out tank(s) and wash with fresh water and/or H-peroxide in place.  Work as small batches in a screened tray.   Capture drainage and loosened minerals and apply outside the ‘system’ such as a soil amendment.
  • When moving qualities of sand any distance, employ mechanical aids such as belt conveyors, containers on roller conveyor, wheeled carts, or sloped chutes or slides (w/ or w/o hydraulic assist) when/where possible.  For smaller volumes, a shovel and wheel-barrow may suffice.

Viable/economic options for (potential) ‘disposal’ of used sand include:  

  • amendment to counteract compaction in clay dense soils.
  • golf-course dressings, turf production soil regeneration.
  • potting soil ingredient.
  • amendment for improved drainage/aeration to ‘organic’ gardeners.

Once we come to grips with the idea that all growing systems (including iAVs) require periodic maintenance, the next question to arise is…”How often will iAVs sand biofilters need to be cleaned?”

The simple answer is that we don’t actually know.  

The investigation of iAVs happened over a period of a couple of seasons.  Similarly, the USDA-sponsored commercial trial was limited to a couple of years.  While the sand biofilters were still operating effectively at the conclusion of the research – and the commercial trials – it is not possible to say with any certainty what their lifespan would have been.

What can be said in support of an extended lifespan is that the commercial trial was conducted with far heavier fish loads than were necessary to support the plants that they grew.   Indeed, the fish biomass in their system was sufficient to support at least double the number of grow beds they used.  That those sand beds were still operating effectively under such circumstances speaks well of their durability.


The 5 Gallon Bucket Tests

iAVs is sand……and sand – at its most productive – is iAVs.

But not just any sand will do.

iAVs sand has 3 essential characteristics:

  • It must be inert – that is it is not chemically reactive.
  • It must be free of silt and clay.
  • It must drain effectively.

The only safe way to know that we have sand that matches these three characteristics is to test it.

To that end, we give you the 5-Gallon Bucket Tests… because, for some of them, we use a 5-gallon plastic bucket.

The tests and measurements that we’ll be carrying out include:

  • Carbonate
  • Turbidity
  • Differential Settling
  • Pore Space Volume
  • Hydraulic Conductivity
  • Water Retention
  • pH

To do these tests, you’ll need:

  • A 5-gallon bucket. Actually, two such buckets would be handy.
  • A measuring jug
  • A clear bottle or a jar with a lid.
  • Freshwater pH test kit that measures 4.0 – 9.0
  • Vinegar.
  • Water
  • Pen and paper – to record the results.

….and let’s not forget…..some sand.

Take one of the 5-gallon buckets and drill sixteen 3/16” (4.5mm) holes in the side of the bucket – at the point where the side meets the bottom.

Sixteen small holes allow for drainage without inhibiting the flow of water.

Vinegar Test

When we talk about the need for the sand to be inert, we mean that it is not chemically-reactive.  That is, the pH of water should not change when it comes into contact with the sand.

Why is pH important?

The pH of water in an iAVs impacts the availability of nutrients. Operating in the range of 6.4 (plus or minus 0.4) ensures that the full spectrum of essential nutrients is available to the plants.

Conversely, the presence of substances in the sand that elevate the pH of the water above the optimum range will mean that certain nutrients are unavailable to the plants.

The most likely influence on the pH of water that comes into contact with sand is that of carbonates.

Sand that contains carbonates is not inert.

Interestingly, the presence of carbonates can be most easily established with plain vinegar.

To conduct the vinegar test, place some sand in the jar lid – and pour some vinegar on it.

To show you how sand containing carbonates behaves, in the presence of vinegar, we collected a sample from a local beach.

The vigorous bubbling evident in this sand tells us that it contains carbonate – is not inert – and is not, therefore, what we’d suggest for use in iAVs.


Turbidity is cloudiness in the water that would indicate the presence of large numbers of individual silt or clay particles that would otherwise be invisible to the naked eye.

The turbidity test is also easy and requires nothing more than a glass jar or drink bottle with a lid.

Half fill the jar with sand and then top it up with water.

Shake vigorously for 5 – 10 seconds and then place the jar on a bench to allow the contents to settle.

This sample suggests the presence of clay. This would be confirmed if the water remained cloudy for longer than a few minutes.
This sample suggests the presence of clay. This would be confirmed if the water remained cloudy for longer than a few minutes.

Differential Settling

Our next test – to establish the proportionate volume of silt or clay in our sample – is the easiest test of all. Simply leave the jar and its contents undisturbed for several hours.

Through a process known as differential settling, we can determine the proportionate fractions of silt or clay in the sand.

Once the sand has settled, any silt will show as a dark line on top of the sand….as evidenced in the photo below.

The black line on the surface of the sand is silt. The floating black layer is organic matter.

Clay, which has the smallest particles, will show as a pale layer above the silt…when it eventually settles.

This sample is free of silt and clay. Note the small amount of powdered sand on the surface. The black lines in this photo are refracted light – not silt.

Pore Space Volume

Having confirmed that our sand is relatively free of silt and clay, our focus shifts to particle size and pore space volume.

The pore space volume refers to the amount of space (for water or air) that exists between the sand particles.

To measure the pore space volume, take the bucket (or other container) without the holes and, using the measuring jug, put 4 US gallons (15 litres) of sand into the bucket.

Then, using the measuring jug, add water to the sand – noting the amount of water that you are adding – until the sand is saturated – or the water is just level with the surface of the sand.

Dry sand of the correct particle size range will have a pore space volume of around 25% – 30%.

If the pore space volume was much lower, that would indicate that the sand contained fine particles – and that might impede drainage.

The real value of the pore space volume test, however, is to demonstrate that sand is not a solid…and that it has space for water, oxygen and the microbial life that powers iAVs.

Another thing to note is that sand will settle for the first few times that it is flooded and drained.  Pore space volume will diminish initially and then stabilise.   The importance of this is that, if your pore space volume is marginal at the outset, drainage could be negatively impacted in future flood and drain events.

Hydraulic Conductivity

Hydraulic conductivity is a term used to describe the ease with which a fluid – in our case water – can move through pore spaces in various media.  Of course, when we speak about media – in an iAVs context – we’re talking about sand.

The flood and drain cycle is important to iAVs because it provides the moist environment required by the plants and the microbial life that underpins iAVs. The drain cycle is equally important because it drives the gaseous exchange – the charge of oxygen-rich air that is also needed by the plants and microbes.

And that brings us to the bucket test. We chose the 5-gallon bucket because it approximates the depth of a sand bed.

Take the bucket with the holes around its circumference and fill it with 4.5 US gallons (18 litres) of sand – leaving a bit of space for the water.

Measure out one US gallon of water into the second bucket (or other container).

We need to measure two things:

  1. The amount of time that takes for the water to enter the sand until it exits from the drain holes.
  2. The amount of water that drains from the sand.

To capture the water that drains from the bucket of sand (so that we might measure it), elevate it within a tub or tray using a house brick or paving tile.

Get ready to time the movement of water from when it hits the sand until it emerges from the drain holes. While the time is not critical, it should be reasonable accurate. You can count aloud if you find that easier.

When you’re ready, pour the water in.

We suggest that you repeat the hydraulic conductivity test 5 – 6 times.

The act of flooding and draining will settle the sand – largely within the first flooding – incrementally reducing the hydraulic conductivity with each subsequent event – until it stablises.

You may observe the level of the sand in the bucket dropping with each flooding. The exact amount of subsidence can be determined by measuring the distance from the top of the bucket to the surface of the sand.

Water Retention

Water retention refers to the amount of water that remains in the sand after the sand bed has drained.

Dry sand might have the appearance of a solid mass but, as we observed during the pore space test, it’s actually about 25% – 30% – by volume – of air.

It’s also important to understand that a quantity of water will remain in the sand following the drain cycle – and it remains there (available to the plants) until the next flood cycle.

The water that remains is bound to the surface of the sand particles by hydrostatic tension.  We’re guessing that amount would be in the range of 5% – 10% of the pore space volume – depending on the particle size and shape.

Note: It will be necessary to top up the fish tank after the sand beds have been flooded for the first time.

After the first flood and drain cycle, the exact amount of water retained in the sand will vary according to the elapsed time from the last flood cycle.

For example, about 5% of the water that was pumped may be retained after the first flood cycle in the morning – after a break of 8 hours or more – whereas only 1% will be retained immediatley after subsequent flood cycles through the day (approximately two hours apart).

Note: These numbers are not prescriptive – they may vary from situation to situation, We use them to illustrate the dynamic nature of the relationship between sand and water in the system.

To establish the water retention of a sand sample repeat the hydraulic conductivity test several times….measuring the amount of water that drains from the sand after each flood cycle.


You complete the assessment or your sand sample with a pH test.

You will have previously established that the sand is free of carbonates with the vinegar test, however, a pH test will determine if there are any other substances in the sand which will impact pH.

Conduct a pH test on the water that you propose to use in your iAVs – before it comes in contact with the sand you’re testing.

Now, mix some of that water with your sand sample.

Any movement of the pH of that water suggests that the sand contains a substance that is chemically reactive. At the very least, this signals the need for further investigation.

Not every one of the tests or measurements that we’ve proposed is essential – but they have been included to help you better appreciate that, when it comes to sand, there’s more going on than meets the eye – and to give you a better understanding of the medium.

Note: Water quality is a critical success factor in any food production regime.  Conducting a full chemical analysis of the water (molecular and elemental) is essential.  These tests can be undertaken, for a nominal fee, by your local country extension office.  In the absence of such a service in your area, we suggest that you seek the assistance of your local university.

Interpreting the Test Results

This article has been all about how to undertake the tests that determine the suitability of sand for iAVs.

In the next article, we’ll test some sand and report on our results….and whether the sand fits the bill.

It goes without saying that, if you do your own tests, we’ll help you to interpret the outcomes.  Simply post in the comments section if you’d like our help.


Where (and where not) to Access Sand.

Now, some places are better to source sand than others.

Our preferred sources of sand include:

  • Quarries – where they actually manufacture sand.
  • Retail outlets – that access their sand from quarries.
  • Cement or Cinder block makers

You may even be able to obtain sand through commercial greenhouse operators in your area.

Regardless of the source, we recommend that you test the sand for suitability for use in iAVs……before you buy and transport it.

The places that we don’t recommend include beaches – because the sand almost always contains calcium carbonate.

The other places that we don’t like are river banks – where the sand is frequently full of pollutants – including pharmaceuticals, chemicals, heavy metals, sewage, and even nuclear waste.



Sand Selection Guide

Given its central role in the success of iAVs, sand is dear to our hearts and is something we’ll be talking about – a lot.

iAVs-suitable sand must be three things:

  • It must be inert – there should be no chemical reaction when the sand comes in contact with water.
  • It must be free of silt or clay.
  • It must drain effectively.

The sand that best satisfies this criteria is crystalline (shar) quartz – silicon dioxide.  Granite – and rounded sand – will work, too.

Sandstone and beach sand will usually contain substances that make it unsuitable for iAVs purposes.  Similarly, flat and flaky sand  is to be avoided.

For comparison, common table salt is 0.1 to 0.3 mm and standard cane sugar is 0.2 to 1.4 mm (w/ 70%+>0.4).

Obviously, the above has been generalized and simplified.  Every sand source on Earth is unique.

Now, that was easier than reading 10 to 20 pages of mind-numbing verbiage, was it not?

NOTE.  In the USA, sand used for quality concrete and/or masonry is called “washed builder’s sand”.

This sand has no salts, carbonates, clays or silt fraction.   These substances can impair the function of a biofilter.

Some quarries will also custom crush and screen to specification if desired and can also wash (more than once if requested) – for a fee.  Delivery costs are almost always greater than the price of the sand itself.   Dry sand weights are approximately 2,850 lbs/cu yd (1.5 MT/cu m).  Do NOT over load your vehicle.

In Montana, ‘good’ sand is $20 to $30/cu yd (depending on quantity) and delivery (8-10 yard loads) costs from $0.30 to $0.50 per mile.  Your smilage WILL vary.

Sand” refers to a specific range of particle sizes.  All of the particles shown in the pictures below (highly magnified) are considered to be sand.  [UPDATED for clarity: The first two images on the left hand side (black background) are of various materials (composition) but are NOT silica (silicon dioxide) (SiO2) sand.  The image to the right appears to be a crushed granite and/or quartz.  Shown here merely to convey that sand is a term for a specific range of particle sizes, and is not indicative of the particular material it could be composed of.  When we refer to sand for use in an iAVs biofilter/sand bed, we mean inert silica (SiO2) sand – and perhaps some volcanic glasses as viable.

sand detail 2  sand detail 1  Sand_from_Gobi_Desert

(click on image to enlarge)


stainless steel mesh screens

Sieve analysis

Keck Sand Shaker– NO affiliation – have not used

” An accurate mechanical sieve kit designed to provide reliable grain size analysis! 20 stainless steel screens including one each of the following U.S. Sieve Sizes: 4, 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 60, 100, 120, 140, 200, 230 and 270.”

MANY online sources.  US$124 on Amazon

Mesh scale unit conversion table

Mesh and screen sources  (registration required)


iAVs Media Fractionation

(click image to enlarge)

iAVs in Oklahoma – #1

I thought I would give all who are interested a recap on my experience with my iAVs in my backyard. Like a good many of you, I have a full-time job, but I long to be out in the greenhouse most of the day/night!


I had operated a deep water culture (DWC) setup starting in 2011, but struggled to keep it productive between temperature swings, bugs and lack of time to attend to the system.  When fall came, it was time to harvest the Tilapia and wait for next spring to get started again…..I really knew that I wanted/needed a greenhouse.

I came upon a German engineer who had designed a greenhouse modeling the Chinese Solar Greenhouse lean-to model which incorporated a DWC system as a part of its energy mass.  As good fortune would have it, I had an opportunity to visit Frankfurt in 2013 during the bi-annual ginormous trade show – ISH-Frankfurt.  My boss and I spent a week exploring the advanced heating technologies that Europe has developed in their mechanical equipment (think Mecca for boiler junkies).  I tracked down Franz via the web and we became email-friendly and he suggested that we spend the week in Heppenheim Germany and take the free train ride into Frankfurt each day to the ISH show – a good plan since hotel rooms in Frankfurt can be $1000+ USD a night during ISH week.  In between daily trade show visits and nightly late drinks in historic Heppenheim’s cobblestone square, Franz would take us around to GHs he had built and show us the energy saving features that he was incorporating into his design.  Very informative and really got the GH construction bug fully energized!

Fast forward to late 2014, I was slowly building out my 24′ x 24′ GH attached to the south wall of my shop building…..following Franz’s general layout for the adapted Chinese design.  My plan was to go DWC rafts again, but when I started following an Aquaponics forum thread discussing the merits of the design-operation of the iAVs.


The greenhouse under construction.


The completed greenhouse.

Fortunately I had not gone too far down the track with the DWC and there was still time to take a fork in the road.  I had chimed in a few times on the Aquaponics thread, but could see that there was way too much drama involved in the discussions.  So, I tracked down Dr Mark McMurtry thru an old email address (thank you Google) and we started trading ideas.  (correction:  I would pose an idea and then I would realize that I need to shut up and take copious notes and try to follow the Jedi Master). Dr Mark was good enough to humor me and help me to see that maybe his 30+ years of iAVs experimentation might save me a lot of dead ends and restarts!

The sand bed before I added the sand.

The sand bed before I added the sand.

Unfortunately, I had installed a full underground SHCS heating/cooling system in the floor of my GH which precluding me from setting the fish tank below grade.  Instead I had to install a shallow sump to collect water that drains from the sand filter grow beds and then pump it back up into the fish tank which sits just inside my shop building (see photo for details).  I say “unfortunately” but in actuality I am quite pleased with the performance of the heating system.  Even with outside temps down as low as 15F, the air blowing thru tubes under the GH keeps the temp inside in the mid to upper 40’s……..all done with less than 200 watts of fan energy!  When the sun comes out even on a 20F day, the greenhouse is floating in the mid-70’s within an  hour or two.

My use of an underground heating and cooling system necessitated a sump tank.

Our use of an underground heating and cooling system necessitated a sump tank.


The sump tank with the cover in place.

The sump tank with the cover in place.

OK, enough background, now on to the star of the show….iAVs.

Finding the proper sand was time consuming, I had gone to at least 4 different sand suppliers before I found a sand that was “in the ballpark”.  After running a 5 gallon bucket perc (hydraulic conductivity) test as directed by Mark, we determined that the “bunker sand” (local supplier’s name for his coarse sand) was close enough to try.  A few more smaller particles than ideal, but overall the profile was decent.  A minimum percentage of clay/silt was a plus.

So… observations regarding the iAVs setup after running for several months.

  1.  Setting the fish tank below grade is best, the extra sump and pump(s) adds complexity to the system and another failure point to have to monitor and repair as needed.
  2.  Not being able to have enough fish/feed load has greatly hampered the growth of the plants.  I am still only feeding my (100) hybrid bluegills about 35 grams of food per day.  Basically just a smidgen over an oz of food per day is all the fish are consuming.  This is hampered by the low fish tank water temperature as I am not heating the water.  When the water temp is over 60F the fish consume about twice as much food, under 55F they are not very interested.
  3. Due to high pH in my source water (Oklahoma City water comes out of the tap at 8.5 this time of year, even higher in the summer sometimes…and the Chloramine has to be neutralized too), the plants are not thriving.  Now they are healthy and green and we have been eating some brandywine tomatoes, leaf lettuce, green beans, broccoli…..but the growth is slow.  I am pretty certain this is due to the 7.4 pH.  I am starting to try to lower the pH (patience is overrated sometimes), so hopefully I will see a big uptick in plant action after I get below 7.0.

February 1st 2016 Update:  I have been slowly dosing with 30 gallons of 6.0 pH water treated with Nitric acid every few days.  Although I can barely see the pH trending down (it maybe 7.3 now) the plants have begun to respond.  The greens, broccoli and lettuce are definitely perking up.  I really think the high pH is due to a high alkalinity in my city water, I plan on getting it tested by a local aquarium supply store to confirm what the true issue with pH “lock” really is.

Although I have been general pleased with the stability and growth in my iAVs system, I know that my pH, low water temp and low feed rate have really hampered the true capability of the iAVs system.  I will try to update as conditions improve.  Present conditions notwithstanding, I am pumped about iAVs.  Simple and robust and inexpensive to operate.




Why iAVs lapsed into Obscurity

Steve Diver’s ATTRA aquaponics document was one of the very few general information sources pertaining to aquaponics – leading up to its renaissance in the mid-2000’s

My recent re-reading of this document revealed some interesting insights including:

  • My initial impression of iAVs was heavily influenced by Diver’s description of “trickle irrigated” – the mental image was nothing like iAVs actually turned out to be.
  • Any reasonable person who read Diver’s accounts of the NCSU System (iAVs) and “the Speraneo Model” would have to conclude that the Speraneo model was an improvement…..particularly given his use of the words
  • The business of selling information packages, seminars and consultancy actually started off with Speraneos.

A few day’s later, Mark asked me why iAVs failed to capture my attention (to the point where I’d investigate it more fully)……and the penny dropped. When I read the North Carolina State University System excerpt, and the one on the Speraneo System, it’s patently clear why the Speraneo system gained ascendancy over iAVs.

Diver’s document was very influential in the aquaponics renaissance in the mid 2000’s… was on Page 1 of Google for years. There must have been thousands of people who read that document and formed their impressions of what aquaponics was about from its contents.

On reflection, I can’t think of any single greater influence on why the Speraneo Model rose to prominence while, at the some time, iAVs slipped into obscurity.

I can still recall how I reacted to the document at the first time I read it – and how it affected my perception around aquaponics…..’til now!


The Case for Organic Certification

In the US, the custodian of organic certification standards is the US Department of Agriculture.  The National Organic Standards Board is an advisory committee comprising organic grower and industry representatives charged with:
  • recommending whether substances should be allowed or prohibited in organic production or handling.
  • assisting in developing standards for substances to be used in organic production.
  • advising the Secretary of Agriculture on other aspects of the organic regulations.

In September 2015,  The National Organic Program established a 16-person task force to explore hydroponic and aquaponic production practices and their alignment with USDA organic regulations.

The task force will prepare a report for the NOSB about the current state of technologies and practices for hydroponics and aquaponics, as well as how those practices do or do not align with the USDA organic regulations. The NOSB will utilize the report to determine the best path forward regarding recommendations on hydroponics and aquaponics production systems.

This is an interesting development because the general view of the organic movement is that if the growing system does not feature soil, it’s not organic.  Several certifying agencies have certified aquaponics systems.  The organic movement want the soil credo reinforced and the commercial hydroponics and aquaponics industries want the standards liberalized.


In almost all developed nations, certified organic produce attracts premium pricing (often 2 – 3 times that of non-organic produce).  The hydroponic/aquaponics folks want some of that action and the organic growers want to keep the club exclusive.

Suffice to say, the battle lines are being drawn.

In this presentation, we put the case for organic certification of iAVs.

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Open Source Food Sustainability

The Integrated Aqua-Vegeculture System (iAVs) is a remarkable food production system.

If we had to encompass all of its attributes in a single word it would be sustainability.

  • It is capable of unparalleled productivity.
  • It generates no waste which is not 100% recyclable (like plant residues).
  • It uses less water than any other food production method – including other aquaponics variants.
  • It requires less energy to build and operate than any other aquaponics system.
  • It’s scalable from the family or village to commercial enterprises.

All of that speaks to iAVs as the food production method of the future…..and it’s FREE for the taking.

That’s right!  We’re not selling anything…..not pumps, fish food, tanks, plan sets, kits.  We’re not even selling information…..not videos, books, seminars.

We’re giving it away……FREE!

If humanity cannot learn to derive its sustenance on this planet in a responsible and sustainable fashion – to coexist with nature rather than consuming it – then what possible hope is there for our  futures?

Mark has given half his life quite literally to this idea……and 30 years after the initial discovery, (and in declining health)  he’s still putting several hours every day into furthering the implementation of iAVs.

He wants nothing more than to see this remarkable technology brought to bear for the benefit of humanity.

We’ll even work with those who want to develop their own iAVs projects.

All you have to do is try it.

So, what’s stopping you?



Is iAVs Really Aquaponics?

IAVs pre-dates aquaponics.  Indeed, the term ‘aquaponics’ was not in use at the time that iAVs was conceived and developed.

The flood and drain gravel media-based aquaponics system started out as a failed attempt to build an iAVs,

OK…but does iAVs function in the same way as a media-based aquaponics system?

Aquaponics is defined as being the integration of recirculating aquaculture and hydroponics.

iAVs is not “hydroponics” since it is not soilless and does not rely on inorganic/ionic solutes for plant growth.  The sand media is an active, complex and highly effective “biofilter”.  Sand + organics + microbes = Soil.

The soil science involved in iAVs precludes its inclusion within the strict meaning of the term “Aquaponics.”

In iAVs, the focus is unabashedly on the plants.  The fish in an iAVs system are the means to the end; the plants are the main game (after the bacteria).  If the soil ecosystem is in good shape (ie…active, diverse, healthy, robust, vigorous), then the fish and plants both benefit.

The sand surface physically removes the suspended solid waste fraction from the aquaculture water.  The soil ecosystem biologically transforms the fish ‘waste’ products (both the solids and solutes) into nutrient forms that vascular plants will assimilate.  The plants perform the function of filter cleaners by extracting their nutrient from the soil and thereby limiting/preventing toxic accumulations.

The central critical aspect of iAVs is a vigorous soil ecosystem, without which the aquaculture water would not be cleansed of toxic waste product accumulations and the plants would not have access to nutrients for their growth.

This diverse and vibrant soil ecosystem is what differentiates/distinguishes iAVs from all other so-called “aquaponics” variants.

That – and productivity, resilience and sustainability.


Is iAVs the Most Water-Efficient Food System on the Planet?

At 7 kilocalories of food per litre of water, iAVs tomatoes and tilapia are 4,000 to 7,000 times more water-efficient than is high-yield corn grown in Iowa (‘not to mention’ the soil loss, energy, Carbon emissions, herbicides and other pollutants flowing down stream).

And, iAVs is 20,000 times more efficient in terms of water consumed per food value produced than is corn grown in SE Missouri – albeit likely destined for combustion in a SUV engine as mandated ethanol-blended gasoline.  Effectively, in the US, we’ll burn absolutely anything, including our food and remaining water resources, just to ‘save’ a few cents on fuel as we drive to Walmart and keep the factories in China pumping Carbon from Australian coal into Earth’s atmosphere.  


And why is this important?

The global water situation is dire – far more dire and imminently catastrophic than most people can comprehend.  And,  it’s getting exponentially worse by the hour.

Globally, two billion (or more) people are currently under severe water stress – and, it’s never going to improve even without the ongoing addition of 230,000 future parched throats and desperate mouths added each and every day (2015).

Globally, industrial agriculture is in deep trouble.

Food production is threatened on every conceivable front.

There’s exponential soil loss, aquifer depletion, extreme droughts and floods, die-offs of bees and other pollinators, mineral (nutrient) constraints, ground and surface water contamination, desertification, increasingly frequent and severe extreme weather events, fossil energy depletion/dependence and exponential mass extinction in every critical trophic level (aspect, component) of the biosphere.

All of these constraints and impacts are set against a rapidly rising human population – long ago in overshoot – and mass extinctions of virtually all non-human life.  Humans are a (rapacious) subset of the biosphere/ global environment aka ‘web of life’, NOT the reverse … as so-called ‘civilization’ obviously ‘thinks’ (acts).  IMO, humans are now the evolutionary/planetary equivalent of full-spectrum cancer.  For those who may not have heard/noticed, cancer kills its host … if fact, this is what imparts/conveys its literal existence.

How come I’m 65% water but only 2% interested?

Stephen Colbert

Some scientists are saying that it’s already too late to prevent human extinction – that we are on an irreversible downward spiral.
Time will tell – but in the meantime, we’ve still got to eat – and that means that we will need to make the best use of every drop of water that comes our way.
Aquaponics is increasingly touted as being water-efficient but let’s not confuse iAVs with aquaponics when it comes to water.  The water efficiency of iAVs is at least 13 times that of UVI raft (DWC) aquaponics – and that doesn’t even account for their failure to factor rainwater into their water use data.
If you’ve made it this far in the article, that suggests you may be interested in the relationship between food production and water use.  Feel free to contact us – or comment – if you want to talk about water use efficiency – or any other aspect of iAVs.
“Adapt or perish, now as ever, is nature’s inexorable imperative.” ~ H.G.Wells

Its impossible to worry about anything else without continual access to potable water – everyone, each and everyday.

“The U.N. also [conservatively] estimates that the world will face a 40 percent shortfall in the global water supply by 2030 unless dramatic steps are taken to improve the management of water. Within a decade, 1.8 billion people are projected to be coping with severe water scarcity and two-thirds of the global population could be living with stressed water supplies.”


The Scientific Method

One of our motivations in developing this site, is to have Aquaponics become a scientific discipline – subject to valid inquiry and elucidation – via the scientific method.

The goal of Science is to know as many true things – and as few false things – as possible.

To that end, we advocate for a thing called the Scientific Method.

So, why is all of this important?

We only have reason (Science) from which to accurately evaluate reality.  One must apply reason (via the scientific method) to know (as distinct from believe) anything.  Reason is not a source (an author, an expert or a deity) – or a dictionary where you can look things up.

Reason (Science) is a method – a way of knowing – and, in fact, it’s the only way of actually knowing anything demonstrable.  The reason we can rely on science is because we can (and do) test it – demonstrate, verify and apply – so that we may know that it works.

Scientific merit also has power in the form of predictive utility, yet another  test for accuracy, efficacy and validity.

We use Science to make sense of things and to improve our lives and possibly (hopefully) our future circumstances.  Science is the way we make sense of things, how to learn what’s real and true (and what is not).  It’s both the how and what we understand from the methodological application of reason.

There are in fact two things, science and opinion; the former begets knowledge, the latter ignorance.


And most of what passes for aquaponics is based on unsupported opinion – or pseudoscience.

Pseudoscience is a claim, belief or practice which is incorrectly presented as scientific, but does not adhere to a valid scientific method, cannot be reliably tested, or otherwise lacks scientific status.

Faith: [is] wanting to NOT know what is true.

Friedrich Nietzsche

And most of what is not abject personal opinion or overt fantasy around aquaponics falls into the pseudoscience category.

So, why is this important?

We’re unaware of any valid experiment or research conducted by anyone … anywhere … since iAVs.

Nor, it seems, is there much in the way of understanding of what “replication” is in any clinical scientific context – nor how or why it is undertaken.

Also lacking is any apparent appreciation/application/understanding of empirical analysis, controls (for/of variables), confidence intervalscontrasts, error, experimental designfactorialsfalsifiability, investigator bias, randomization, rigour or significance.

One-off of anything proves absolutely nothing.   And repeating it (regardless of how many times that happens) still establishes or “proves” nothing in a scientific context.

This is particularly the case with something of the complexity of a multi-trophic ecosystem.

Whatever it might be anti-academic bias, deception, distortion, egomania, faith, fraud or habit, it’s not Science.

“Faith is belief without evidence in what is told by one who speaks without knowledge, of things without parallel”.

 Ambrose Bierce

Aquaponics will never become a discipline or a viable technology (much less be implemented at any meaningful scale) by continuing to apply the haphazard, bungling and wilfully ignorant approach of the past 25 years.

Sponsors and supporters are desperately needed from within the following disciplines:

  • aquaculture sciences
  • aquatic ecology
  • horticultural science
  • applied genetics
  • soil ecology and sciences
  • hydrology and water conservation
  • microbiology
  • nutritionists (aquatic, botanical, and human)
  • integrated pest management
  • controlled environmental engineering and management
  • eco/biological synergism and systematics
  • dynamic systems management
  • phycology
  • marketing and distribution of perishable commodities
  • post-harvest technologies and food safety regulation

So, let’s start that with a look at how the scientific method works.

  • Ask a non-trivial, specific question
  • Do comprehensive and relevant background research
  • Construct a testable hypothesis
  • Test Your hypothesis through experiment(s)
  • Analyze Your data and draw a conclusion
  • Communicate your results – in a relevant, refereed format and cite sources for all non-original content

Engineering (applied sciences) utilizes a similar approach known as the Engineering Design Method.

Once we’ve got a bit of scientific research and development happening, it’s probably time to invite the enterprise, investment and development sectors to the party.

All great truths begin as blasphemies.

George Bernard Shaw

Application of the Scientific Method – aka The Conduct of Analytical Research

1. Purpose: Identify what you want to know, learn, understand, establish, develop …  and why.

2. Investigation : Learn the prevailing state of knowledge within the subject area and pertinent topics

3. Hypothesis: Formulate testable hypothesis – designed to resolve answer(s) to a specific question

4. Experiment: Test hypothesis by the development and conduct of appropriate methodological tests (applicable/valid experimental design, to include relevant and significant checks, controls and sample sizes).

5. Analysis: Access experimental results with appropriate/valid methodology.  This virtually always requires application of relevant statistical analysis (requiring both multiple replicated (confirming) and contrasting (divergent) data sets).

6. Conclusion:  Support all conclusions with significant (statistically probable, verifiable) findings.

7. Publication: Subject the applied methodology, findings, analysis and conclusions reached to scrutinization (acceptance or rejection) by anonymous (non-vested) professionals qualified to assess competence and validity within the given subject area.

“What can be asserted without evidence can be dismissed without evidence.” ~ Christopher Hitchens


The Economics of Organic Certification

OK…..let’s kick this article off with some facts:

  1. Aquaculture is an established, profitable, rapidly expanding industry.
  2. Greenhouse horticulture (including hydroponics) is a highly developed viable commercial enterprise globally.
  3. ‘Organic’ fruit and vegetables are in high demand and realize substantial price premiums in most Western markets.

Commercialized iAVs represents the symbiotic integration of  1, 2 and 3 above.  The economic outcome is greater than sum of its parts:

The big stumbling blocks to organic certification of ‘aquaponics’, it seems, are the various soilless plant growing ‘systems’ being advocated.  While a couple of bold certifiers have overlooked this part of the organic credo, the majority of organic certifiers have made it clear that if it isn’t growing in soil, then it isn’t “organic” – and it won’t be getting certified.  iAVs uses inert sand (Silicon dioxide) as the growing media.

Sand + organics + microbes = soil.

This means that the soil ecosystem (media) used in iAVs is consistent with organic certification – without all of the argument that will invariably attend soilless culture.

Another important factor is that of the 2 – 3 year withholding period from the first expression of interest to the time one can actually hang out their organic shingle.

If you can demonstrate, however, that the sand is derived directly from a pristine rock source (‘virgin’ granite or quartz) – and subsequently is contained in an impervious food-grade liner inside a controlled environment (like a greenhouse) – it seems logical that you should be able to reduce the withholding period to as little as a few months.

The point is that you’ll have to satisfy the certifiers that there is no risk of contamination with existing soil – nor potential contact with other pollutants (such as carcinogens, GMO pollens, herbicides, insecticides, heavy metals, ozone, radio-isotopes, etc.)

To the moist, oxygenated sand is added complex organic nutrient precursors (fish ‘wastes’ ) plus water.

The super oxygenated sand plus organic ‘wastes’ results in a complex interactive rizosphere and vibrant soil ecology comprising hundreds (if not thousands) of  micro/macro-fauna species.

Together, this matrix of moist inert sand particles, plus complex organic compounds, plus supercharged aerobic soil organisms = soil.

Why is all of this important?

Organic produce wholesales at two to three times the price of non-organic produce.  

So, how does certification impact a business model and enterprise viability?

For the answer to that, let me refer you to Mark.

“Non-organic CEA-GH profitability – presuming competence and developed markets – is an established, proven enterprise model.

Any given production area (A), times the mean yield rate (Y), times the mean unit price received (P) = Gross value produced per unit interval.

(A x Y x P) = G

Gross sales (G), minus Fixed costs (F), minus Operating expenses (O) = Net profit (N).

G – (F + O) = N

The direct relative comparisons below presumes similar location(s),  same land, structure, energy, finance, regulatory and labor unit costs, fish feed ≈ soluble nutrient costs,  same post-harvest and distribution/marketing unit costs, etc.]

For a state-of-art CEA Hydroponic tomato venture:

  • set values: A , Y and P  each (all) to 1   (100% of any area, yield and price values you’d accept as reasonable/valid.)
    • therefore,  G = 1.0 (100%)  – at whatever scale, yield and unit price you ‘want’ (presume)
  • set F to 0.3 (30%) and O to 0.6 (60%), relative to gross production value derived:
    • therefore, N = (1 – 0.9) = 0.1 = net margin of + 10% of gross sales  (approximate best case scenario for hydro grown tomato)

For a state-of-art CEA iAVs tomato operation, relative to above CEA Hydro tomato production:

  • iAVs Scenario A (without any fish sales or any fruit yield gains – or intercrops):
  • set values A = 1, Y = 1 (same as Hydro) and P = 2.5  (median premium received for Certified Organic product)
    • therefore, G = (1 • 1 • 2.5 ) = 2.5 = 250% (of prevailing non-organic production gross value)
  • set F [relative to Hydro G above (typ.)] = 0.4 (to incl. added cost of aqua related devt./equipment)
  • set O [relative to Hydro G above (typ.)] = 0.7  (to incl. added cost of aquaculture operations)
    • therefore, N = (2.5 – 1.1) = 1.4 = net margin of +140%  (14 times the profitability of non-organic.)
    • i.e., employ $1.1 to generate $2.5, ‘keep’ $1.4
  • iAVs Scenario B – median case – ( with fish sales at 10% of gross, +10% fruit yield gain, median premium)
  • set A = 1, Y = (0.1 + 1.1) = 1.2, and P = 2.5
    • therefore, G = (1 • 1.2 • 2.5) = 3.0
  • set F = 0.4 and O = 0.7 (as above)
    • therefore, N = (3.0 – 1.1) = 1.9 = net margin of +190%  (19 times the profitability of non-organic.)
    • i.e., employ $1.1 to generate $3.0, ‘keep’ $1.9
  • iAVs Scenario C – worst case – ( with fish sales at 5% of gross,  10% fruit yield reduction, low price premiun)
  • set A = 1, Y = (0.05 + 0.9) = 0.95, and P = 2.0
    • therefore, G = (1 • 0.95 • 2) = 1.90
  • set F = 0.4 and O = 0.7 (as above)
    • therefore, N = (1.9 – 1.1) = 0.8 = net margin of +80% (8 times the profitability of non-organic.)
  • iAVs Scenario D – best case –  (with fish sales, +20% yield gain, and top premium (skilled marketing) received
  • set A = 1, Y = (0.1 + 1.2) = 1.3,  and P = 3.0
    • therefore, G = (1 • 1.3 • 3.0) = 3.9
  • set F = 0.4 and O = 0.7 (as above)
    • therefore, N = (3.9 – 1.1) = 2.8  = net margin of +280% (28 times the profitability of non-organic.)
    • apply/employ $1.1 to generate $3.9, ‘keep’ $2.8
  • iAVs  Scenario E – socially responsible case –  (with fish sales, +10% yield gain, low price premium received plus better than ‘living wage’ w/ benefits including medical paid to laborers (vs. minimum wage ‘slaves’)
  • set A = 1, Y = (0.1 + 1.1) = 1.2, and P = 2.0
    • therefore, G = (1 • 1.2 • 2.0) = 2.4
  • set F = 0.4 and O = 1.0 (to include increased wages and benefits paid)
    • therefore, N = (2.4 – 1.4) = 1.0  = 100% net margin  (10 times the profitability of non-organic.)
    • apply $1.4 to generate $2.4, ‘keep’ $1.0, ‘contribute’ $0.3

Clear as a septic tank?  Right?

OK…..if you’re like me, you might find a graphical representation useful.

Area of the squares (below) are directly proportional to the dollar value produced (G = market value) per unit area/time.

  • Fuchsia = the proportion of gross income that is a Fixed cost
  • Orange = the proportion that is an Operating expense.
  • Green = the relative Net margin (profit).

Gross G = 1X represents a typical commercial hydroponic tomato grower’s costs and returns. The larger areas represent some of iAVs scenarios explained above.

Relative Profitability

What the graphic illustrates is that the effect of doubling (or greater) one’s sales price has a FAR greater positive effect than merely doubling the bottom line (profitability).

Optimising marketing has a far greater effect on favorable investor returns than does the grower’s ability (expressed in terms of the yield level).

So, why is that important?

As an investor, would you rather receive a 10% return on your capital – or 100% – or 300%?

Let’s be clear, there are no yield claims or unit value assumptions applied here. It’s a simple direct comparison of one methodology – and the range of unit market value – relative to the other.

If it is not already obvious from the above, note that the value of fish production in iAVs represents from 5 to 10% of the total Gross valuation generated.  Therefore, it is my/our assertion that iAVs is economically dominated by  “Organic Olericulture”, aka Horticulture first, second and probably third.  In economic terms, the fish production is largely irrelevant excepting the benefit provided by their ‘waste’ products following botanical-availability (bio-conversions) occurring in the soil ecosystem.

If commercial hydro-grown tomato is profitable, then from 8 to 28 times GREATER profitability per unit area/time is the difference that organic certification makes.

And the aquaponics methodology best suited to organic certification?

You guessed it…..the Integrated Aqua-Vegeculture System – iAVs.

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