The Aquaponics Fork in the Road

This is Chapter 4 of The Urban Aquaponics Manual – 4th Edition.

In a Chapter 2, we looked at how aquaponics works from a basic microbiological perspective…and I said a properly-designed aquaponics system was a recirculating aquaculture system (RAS) to which growing systems were (loosely speaking) attached.  Consistent with that direction, Chapter 3 looked at the filtration methods that are at the heart of a RAS.

Then I revealed that there was this creature called the basic flood and drain system…where media grow beds allegedly doubled as the filtration system.

Here’s where I explain what I meant when, back in Chapter 2, I referred to “informed decisions” – and here’s where you get to make what is arguably the most important choice that you will make with respect to aquaponics.

First the explanation…

The Basic Flood and Drain System

The Basic Flood and Drain System (which I also refer to as the Speraneo model) comprises a fish tank, a pump and a grow bed that contains media like gravel, expanded clay pebbles or lava rock.

The water is pumped from the fish tank up into the grow beds. Once the water reaches a predetermined level it drains back into the fish tank.

Basic+FD

It’s simple to understand, easy to build and operate – and (within particular constraints) it can work.

It should come as no surprise, therefore, that the basic flood and drain system is the most commonly used backyard aquaponics system in the world.

Tom Speraneo inadvertently discovered that he could take a gravel grow bed (long used in hydroponics circles) and adapt it to:

  • capture and mineralise the fish solids.
  • facilitate nitrification
  • aerate the water
  • grow plants.

It all sounds very positive, so far. So, what’s the problem?

Well, there are several actually but, before we get into those, it’s appropriate that we should learn a bit more about how the Speraneo model came into being.

Aquaponics Biggest Mistake

Many people who are interested in aquaponics know that Missouri farmers Tom and Paula Speraneo popularised what is commonly termed as flood and drain aquaponics.

For the uninitiated, flood and drain aquaponics in its simplest guise comprises a fish tank and one or more media (usually gravel) grow beds.  Nutrient-rich water is pumped from the fish tank into the gravel grow beds before draining back into the fish tank.

What far fewer people know is how the Speraneos came to be involved in aquaponics and where the idea for their basic flood and drain system originated.

In the mid-1980’s, Dr Mark R McMurtry invented the Integrated Aqua-Vegeculture System (iAVs) – the first successful ‘closed loop’ production of vegetables using the metabolic wastes of fish.

iAVs comprises a fish tank and sand biofilters (in which the plants are grown).  It’s simple to understand, easy to build and operate – and it definitely works.

Following the completion of his PhD dissertation at North Carolina State University, McMurtry undertook a series of trips to showcase iAVs and its benefits for allied faculty staff, students and aquaculture industry professionals.

In December 1989, one such trip to Arkansas put McMurtry in contact with Tom and Paula Speraneo at the University of Arkansas in Little Rock.

A week later, he facilitated a 3-day interactive discussion/workshop at the Meadowcreek Project in Fox, Arkansas for the usual mix of faculty, staff, students and other interested parties – including the Speraneos.

The Speraneos returned home keen to construct an integrated aquaculture system based on what they’d learned from its inventor.

As it turned out, they weren’t able to afford the sand that was central to iAVs’ effectiveness, so they dug up their gravel driveway for use in their system bio-filter.

Let’s remember that the efficacy of iAVs relies on the use of sand (not gravel) so this was a significant change and one that would have serious implications for iAVs – and aquaponics.

Meanwhile, oblivious to the fact that his work was about to be usurped by a mistake, McMurtry had begun a promotional tour of sub-Saharan Africa and Middle Eastern countries.

When he returned, he became aware of the Speraneo’s substitution of gravel for the sand and he counselled them at length about their choice – but they persisted.  This aberration would subsequently be popularised as the flood and drain aquaponics system.

This “mistake” – subsequently to become wilful ignorance – was what best-selling author Malcolm Gladwell would later describe as a “tipping point” – one that would have profoundly negative implications for aquaponics.

The sand bio-filter is the heart of the iAVs “living machine.”  The substitution of gravel for sand impacted the design in several ways including:

  • a dramatic reduction in mechanical filtration capability
  • a dramatic reduction in soil microbial types and population numbers
  • reduced aeration of media bacteria and plant root zone
  • reduced nutrient utilization and system stability
  • a significant reduction in feed conversion rate and fish growth
  • increased capital costs with reduced fish and plant yields
  • increased risk profile
  • increased operating cost per unit of production

One of the key features of the iAVs design is its versatility.  A backyard farmer – or an impoverished villager – or a protected cropping greenhouse operator could use the same system design.

The first casualty of the change in media was iAVs‘ commercial potential.  The basic flood and drain system never gained commercial traction because gravel does not lend itself to the mechanisation and automation that is a feature of controlled environment agriculture.  Sand, by contrast, had been used in hydroponic greenhouse culture for decades – subject to all of the usual constraints associated with greenhouse culture.

The iAVs could be built and operated by a humble villager with some seeds and relatively little guidance.  The basic flood and drain system, by contrast, requires a connection to the grid, a pump (or two) and ongoing access to mineral supplements.   The basic flood and drain system also required greater skills and knowledge to offset the heightened risks that it poses.

As an aside, the Speraneos (who initially gave credit to McMurtry for their introduction to what was yet to become known as aquaponics), eventually used their utilisation of gravel as a point of sufficient difference (in their minds at least) to assume ownership of the concept.

This process of taking a system design and “tweaking” it (with a view to assuming ownership of the idea that underpins it), was to become a recurring theme in aquaponics.

Anyway, the Speraneos developed an information package and promoted their system through an Internet mail list (the fore-runner of the discussion forum).

Interestingly, when this information package first became available, purchasers were asked to agree (by way of a binding legal instrument) not to market their own information packages. It seems that the Speraneos were not keen to have done to them what they had done to McMurtry.

This requirement obviously lapsed at some point because, in 2005, Joel Malcolm bought the Speraneo’s information kit and “tweaked” it into an Australian context.  Australia’s ABC Gardening TV program ran a segment on Malcolm’s home-based system and the basic flood and drain system enjoyed a new surge in popularity.  Regrettably, however, the “new” flood and drain system had the same basic flaw – the media particle size.

Various other kit makers (including Murray Hallam and Sylvia Bernstein) adopted the Speraneo flood and drain system and, while they “tweaked” the model too, none of them managed to grasp the toxic tipping point – the gravel instead of sand.

To summarize, the substitution of gravel (or clay pebbles) for sand was not just a minor detail – it was the aquaponics difference between chalk and cheese.   The iAVs is a living machine whereas the basic flood and drain system is, given a convergence of common (indeed likely) events, a killing machine.

In terms of its filtration efficacy, McMurtry has characterized the use of gravel to capture solids in the biofilter as “attempting to catch BB’s with a basketball hoop.”

It’s important to understand that the difference between iAVs and the Speraneo model is much more than one being usurped by the other…or any philosophical notion.

The basic flood and drain aquaponics system was/is nothing more than a big mistake – an unfortunate mutation with nothing like the productivity, resilience and versatility of its iAVs predecessor.

Anyway, this manual is about aquaponics and, since iAVs is not aquaponics, it’s time to focus on the technical issues of the Speraneo model.

Earlier, I said that the basic flood and drain system relied on the gravel grow beds to:

  • capture and mineralise the fish solids.
  • facilitate nitrification
  • aerate the water
  • grow plants.

The simple fact is that the capture and mineralisation of fish solids in the gravel grow bed is at odds with the nitrification and aeration functions of the grow bed.

In other words, particulate matter consumes oxygen – and, in certain circumstances, inhibits the conversion of ammonia into nitrite and (subsequently) nitrate. The greater the quantity of this particulate matter, the greater the amount of oxygen that is required to deal with it.

For an understanding of how this happens, let’s hark back to what we said about ammonia when we looked at the aquatic nitrogen cycle.

“As the fish digest food, they produce solid wastes – and they include urea, uric acid and faeces. Uneaten food also contributes to the solid wastes in the system.

These solid wastes eventually yield ammonia – through a process known (not surprisingly) as ammonification.

The family of bacteria that facilitate this conversion of organic nitrogen into inorganic ammonia are called heterotrophs.”

Not bloody Heterotrophs again?

Heterotrophs are as essential to the operation of any aquaculture/aquaponics system as autotrophs – the nitrifying bacteria – however the relationship between the two types of microorganisms is not without its problems.

The first issue is the rate at which their numbers grow – relative to each other.   Autotrophs multiply relatively slowly – where heterotrophs multiply very rapidly.

This means that heterotrophs can overwhelm autotrophs – indeed eat them – to the point where nitrification is stalled.

OK, so what is likely to cause heterotrophs to multiply to the point where they might actually inhibit nitrification?

The answer is solid wastes – in the form of urea, uric acid, faecal matter and uneaten food.

More solids = more heterotrophic activity.

The other issue is that rapidly multiplying heterotrophs consume large quantities of oxygen from the water.

So, the problems for the fish are twofold – they can run out of oxygen and/or, in the event that nitrification is stalled, they’ll be affected by ammonia toxicity.

We’ll look at the role of oxygen in aquaponics, in depth, in the section titled “Managing Water Quality.” At this stage, it’s sufficient to know is vital to the survival and wellbeing of fish, plants and beneficial bacteria.

Once dissolved oxygen in the water drops to sub-lethal levels, fish begin to die – quickly. Even if they don’t quite reach that point, low dissolved oxygen levels stress fish – and stressed fish are more prone to disease and parasitic infestation.

In fact, low dissolved oxygen levels (or stressors arising from low DO) are the leading cause of fish deaths in aquaponics systems.

OK…so what’s the solution to the solids issue?

The best way to deal with sedimentary and suspended solids is to capture and remove them from the water column.

Now, this viewpoint flies in the face of aquaponics fundamentalists who argue that the solids contribute to the overall nutrient mix in an aquaponics system. They contend that the solids will be trapped in the grow bed, mineralized by composting worms and eventually become part of the nutrient mix.

While I don’t argue with the basic mineralization proposition, here’s why I suggest that solids be removed:

  • Bio-filters (including grow beds) function more efficiently when solids are removed.  
  • Both fish and nitrifying bacteria require oxygen. Fish wastes and uneaten food consume oxygen and, in extreme situations, will drive dissolved oxygen levels down to the point where fish can no longer survive.
  • Built up fish wastes create pockets of anaerobic (without oxygen) activity resulting in de-nitrification – the opposite of what we’re trying to achieve.
  • Grow beds will require less frequent maintenance if solids are removed. Regardless of how many worms you have in a grow bed, there will still be some sediment left in the bed. Over time, this sediment will (unless removed) build up and will eventually impair the biological functionality of the bed.
  • Solids irritate the eyes and gills of the fish – and stress them. Stressed fish become more susceptible to disease.
  • Solids can harbour harmful pathogens.
  • Working with clean grow beds (and clean hands) is a more pleasant task.

OK…but, by removing the solids, aren’t we wasting nutrients that would otherwise be available to our plants?

First, we need to understand that there are three types of solid wastes – dissolved, suspended and sedimentary. The dissolved solids – and the smaller fraction of the suspended solids – remain in the water and undergo ammonification and nitrification.

Indeed, up to 75% of the wastes produced by the fish in the system – having passed across their gills – are in the dissolved form. Put another way, up to 75% of the nutrients in the water are in dissolved form.

Second, the simple fact of removing the solids ought not infer that we are wasting them – quite the contrary.

The solid wastes can/should be processed so that they deliver up any remaining nutrients. The nutrient-rich water is then decanted from the sludge and returned to the aquaponics system.

The remaining sludge contributes nothing useful to the system. In fact, it can harbour harmful pathogens and irritate the fish’ eyes and gills and the best place for it is the compost heap or the worm farm.

OK…..so what prompted the confusion around the removal of solids in the first place?

A Matter of Dogma

Earlier I said that the basic flood and drain aquaponics system was the most commonly used backyard layout in the world.

That begs the question…“If it’s so problematic, why are so many people using it?”

Fair question…and here’s the answer…

  • Few people knew about it’s iAVs heritage. For several reasons, Mark McMurtry wasn’t around to defend the iAVs method and, while the Speraneos knew about it, they obviously decided that it wasn’t in their interests to press the facts around iAVs.
  • Its inherent simplicity appeals to people. It’s easy to understand, build and operate…and it works (right up to the moment that it doesn’t).
  • During its rise to worldwide prominence, kit manufacturers owned three out of the four largest aquaponics discussion forums in the world, and they promoted it as the aquaponics ideal. They exploited the fact that it’s easier to sell something if you don’t confuse the purchaser with all of the things that could go wrong.
  • Most of the people who set out to build the layout didn’t understand its pitfalls – they got caught up in the hype and simply didn’t know what they didn’t know.

As far back as 2007, I argued in support of the use of dedicated mechanical and biological filtration in media-based aquaponics systems.  I met with such a barrage of criticism from aquaponics fundamentalists that I built four basic flood and drain systems side-by-side.  Over a period of nine months, I trialled three Australian native species – and a diverse range of plants – in these units.

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The pretty picture belies the biological unhappiness that’s happening in the fish tanks.  This is the truth of the basic flood and drain system – it’s presentation as a sustainable way to grow food is largely an illusion.

To summarise the outcome, most of the plants grew very well.  Regrettably, the fish suffered almost from the outset.

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Plant production was no issue with the basic flood and drain systems that I built but, the presence of sedimentary and suspended solids means that there’s a heightened risk of disease and death for the fish.

To summarise…the basic flood and drain system is a very bad idea…particularly for fish. It was the product of wilful ignorance and it continues to be aquaponics’ biggest mistake.

For those who are attracted to the basic approach, my advice is to learn about the Integrated Aqua-Vegeculture System (iAVs), build the real deal…and reap the benefits.

The Improved Basic Flood and Drain System

For those who want to persist with gravel (or clay pebbles, lava rock or other coarse media) grow beds, I still recommend that they be thought of as hydroponics growing units to be attached to a recirculating aquaculture system.

Improved+FD

The inclusion of mechanical and biological filtration will make a vast difference to a basic flood and drain system. From the fish’ perspective, it’s probably the difference between life and death.

So long as you have an effective means of capturing the sedimentary and suspended solids, you can utilise the gravel grow bed as a biofilter.  There are still advantages, however, to including a dedicated biofilter into your design and we’ll explore those in detail in the next section.

So, having put what I hope is a reasonable case for using a recirculating aquaculture system as the basis for all aquaponics systems, it’s time to head over to Chapter 5 – Designing Your Recirculating Aquaculture System.

-o0o-

In the meantime, I invite you to comment…to express any concerns that you may have…and to provide ideas or suggestions that you feel will improve the book – or add value to it. 

Understanding Filtration

This is Chapter 3 of The Urban Aquaponics Manual – 4th Edition.

In the previous chapter, we looked at how aquaponics works from a basic microbiological perspective.

In this section, we learn how to optimise the conditions under which the beneficial bacteria work – in the best interests of fish health and wellbeing – from a practical perspective.

Fish wastes take three forms:

  • Sedimentary – usually comprise fish faeces and uneaten food that will settle out if water velocity is low enough.
  • Suspended – small particles of food or faeces that are neutrally buoyant – they neither sink nor float but are carried in the water flow.
  • Dissolved – largely ammonia arising out of the gills or generated by the mineralisation of fish wastes – they are in solution.

Filters are the means by which we optimize water quality for our fish…by capturing sedimentary and suspended solid wastes and/or converting the dissolved wastes that they produce – which would otherwise eventually prove toxic to them – into a more manageable form.

A good filter will be:

  • Made of inert, non-toxic materials
  • Inexpensive to build
  • Easy to operate and maintain
  • Reliable
  • Space-efficient

The devices that we use to capture solids are mechanical filters and those that we use to oxidize (nitrify) dissolved wastes are biological filters.

Mechanical Filters

Mechanical filters include:

  • Sedimentation tanks
  • Clarifiers
  • Swirl tanks
  • Radial flow separators
  • Packed media filters

This list is far from exhaustive but these are the filtration devices most commonly used in small-scale aquaculture.

Sedimentation Tanks

Sedimentation tanks serve to reduce the velocity of the water flow so that sedimentary solids will settle to the bottom where they can be removed. In essence, the longer the water remains in the sedimentation device, the greater the volume of solids that will settle out. The minimum retention time is 20 minutes – more is better.

For example, if the fish tank is 1,000 litres – and the flow rate is 1,000 litres per hour – then the sedimentation tank should contain not less than 330 litres of water.

Some sedimentation tanks are fitted with weirs to assist the settling process. 

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This is a variation on the sedimentation tank idea.  The water passes under the first weir – over the second one – under the third weir and over the final one.

Clarifiers

Clarifiers (not my preferred name for them) are another form of sedimentation tank. They usually comprise a round tank with a cone-shape bottom and they are fitted with baffles that direct the water flow downwards – with the idea that the solids keep travelling toward the bottom.

Like all sedimentation devices, clarifiers rely on a reduction in water velocity to function effectively…with the added effect of directing the watery solids downwards.

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This is a clarifier of the type used at the University of Virgin Islands Aquaponics Research Center. The water enters the small chamber and is forced downwards.  As it enters the second chamber, it is forced even further downwards – causing the sedimentary solids to settle in the clarifier apex.

In my view, there are other sedimentation devices that are easier to build and are more efficient in their use of space.

Swirl Tanks

Swirl Tanks rely on centrifugal action (specifically the ‘hydro-cyclone effect’) to force heavy particles (solids) to the outside of the tank where they then settle to the bottom for easy removal. 

Swirl+Filter

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This is an inside view of a swirl separator.  The water enters via the 90 degree bend and exits through the pipe on the left.   An upright pipe (removed for viewing clarity) sets the level in the tank and serves as a weir.

Swirl filters are easy and cheap to build but radial flow separators are much more efficient – and they are no more expensive nor difficult to build.

Radial Flow Separators

The water (containing particulate matter) flows from the fish tank into the centre of the radial flow separator where it is forced downwards. The water velocity drops abruptly at the change of direction and the solids continue downwards and settle out while the clear water exits the separator via the overflow weir.

Radial+Flow+Seperator

Packed Media Filters

Packed media filters are designed to trap suspended solids – those that maintain neutral buoyancy – and carried around the system in suspension. There are a variety of different types including manufactured media (using Kaldnes K1 – or similar – filtration media), filter mats and brush filters.

Packed media filters function by allowing the water to pass through various types of static media.  After a short time in the water, the media in the filter will become coated in a sticky substrate – biofilm.  As the water passes through the filter, the suspended solids adhere to the biofilm where they remain until the media is cleaned.

There are various types of media used in these devices including:

  • Bird netting
  • Matala Mat
  • Filter Brushes
  • Manufactured plastic media

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Nylon bird mesh is inexpensive and effective at trapping solids – but cleaning it is an ordeal.

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Matala mat comes in different densities (denoted by colour). It’s effective at capturing solids, is more expensive than bird netting but easier to clean.  This box filter (used in a small commercial system) utilises Matala mat to good effect.

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Brush filters are effective at trapping suspended solids, relatively inexpensive and easy to clean.  They are suspended in a barrel so that the solid-laden water flows up through the bristles. The suspended solids adhere to the ‘sticky’  biofilm.

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Manufactured plastic media (in this case, Kaldnes K1) is just as effective in a static packed media application as it is the moving bed bio-reactors for which is was originally designed.  It offers high specific surface area (to produce a correspondingly large space upon which biofilm forms) and cleaning it is as simple as ‘boiling’ it with air.  This causes the tiny sections of media to rub against each other – dislodging the accumulated solids – which are then easily drained from the filter.

There’s a wide range of off-the-shelf filtration devices including:

  • Rotating drum filters
  • Screen (sieve) filters
  • Fluidised bed sand filters
  • Bubble bead filters
  • Cannister filters
  • Vortex filters

Some of these are very effective (others less so) and those that are effective are priced accordingly.  To be candid, you can achieve perfectly acceptable water quality – for a lot less money and hassle – with the DIY options that I’ve described.

Biological Filters

Having got the bulk of the solids out of the system, it’s then time to facilitate ammonification of any remaining suspended and dissolved solids – and then to convert the ammonia into nitrites and subsequently into nitrates.

Biological filters are simple devices that facilitate the colonization of the beneficial bacteria that are central to recirculating aquaculture. As the fish tank effluent passes through the biofilter, the remaining solids are exposed to the bacteria that facilitate nitrification.

Other by-product bio-filter functions include:

  • Oxygenation of the water
  • Removal of CO2
  • Flashing off of nitrogen in gaseous form

For small-scale aquaculture purposes, there are two main types of biological filter:

  • Trickling Bio-filter
  • Moving Bed Bio-filter

There are other types of biological filters including rotating biological contactors, bead filters, and fluidized bed sand filters….but those that I’ve listed are those best suited to backyard fish farmers – in the short term at least.

Trickling Biofilter

Trickling biofilters have been around for more than 100 years.

They were still widely used in wastewater treatment plants when I trained as a wastewater treatment operator in the 1970’s.

The huge trickling biofilters, with which I worked, used rocks (about 150mm or 6” in diameter) as media. A rotating boom arrangement ensured that the effluent was distributed evenly across the media.

The rock media served as the substrate to which the bio-film attached and the nitrifying bacteria lived in the bio-film.

The charm of trickling filters is that they are simple to build and easy to operate and maintain. They work well across a wide range of nutrient levels.

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Trickling biofilters are simple devices that cost little to set up and are easy to maintain.  This small stand-alone recirculating aquaculture system was used to grow out jade perch.  A pump (ln the fish tank) pushed the water through a cannister filter and up to the manifold supplying the biofilters.  The water then percolated down through the oyster shell media before draining back out into the fish tank.

The percolating action of the water as it trickles down through the media provides for excellent aeration. It also facilitates the removal of carbon dioxide and nitrogen (in gaseous form) from the water column.

Choosing the right media is also an important design consideration. Media options include:

  • Oyster shells
  • Manufactured plastic media
  • Coarse gravel or river pebbles
  • Light expanded clay aggregate (clay pebbles)
  • Scoria/lava rock

Oyster shells are our preferred media – they cost nothing and never clog. 

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The downside of oyster shells is that, compared to other media, they have a low specific surface area (SSA).

*SSA refers to the amount of surface upon which the biofilm that houses nitrifying bacteria.  SSA is measured in terms of square feet/cubic foot or metres/cubic metre.  In other words, if you were to lay all of the exposed surfaces of a given quantity of media (a cubic foot or a cubic metre) flat, the SSA would be the number of square feet or square metres that you’d have.

My next choice would be Kaldnes K1 manufactured plastic media.  

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Kaldness K1 is, compared to some other media, relatively expensive – but it has a very high SSA.  It can be used to good effect in packed media filters, trickling biofilters and moving bed bio-reactors.

Good nitrification will depend on effective water distribution throughout the filter.   Large commercial biofilters often feature rotating spray arms. Small units will often have a deflector arrangement that spreads the water across the top of the filter media.

We made an inexpensive water distributor out of a plastic bowl in which we drilled holes. It functions like an oversized shower nozzle spreading the water evenly over the media. Another option is to drill 8mm holes in a PVC end cap (like a crude shower fitting) and mount the cap so that it sprays the water across the media.

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Trickling biofilters rely on even distribution of the solids-laden water across the media.  We made an inexpensive water distributor from a cheap dishwashing bowl into which we drilled holes.  The bowl functioned as a sort of shower head and spread the inflow evenly across the media.

Moving Bed Bio-Reactor (MBBR)

While we started out using trickling biofilters, we’ve gradually transitioned to the moving bed bio-filters pioneered by Anox Kaldnes.

An MBBR consists of a barrel – or tank – filled with water to which 2/3 by volume of Kaldnes K1 media is added.  The water is aerated using air stones or a diffuser.

Moving+Bed+Bio-Reactor

Initially, the media will float because (like all polyethylene or polypropylene) it’s hydrophobic – it repels water.

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The media in a new MBBR is (slightly) positively bouyant.  That changes once the media has assumed the loading of a fully functioning unit.

In the weeks following the commissioning of a new filter, however, biofilms will establish themselves on the exposed surfaces of the media…and the nitrifying bacteria will begin to colonise the filter.  The subsequent increase in loading moves the media closer to neutral bouyancy – to the point where it takes on the characteristic slow rolling action of a functional MBBR.

Getting an MBBR operating properly will take longer and require greater effort than a trickling filter – and, depending on the media choice, it will cost more to build.  

The reasons that I now use them, however, include:

  • The creation of an oxygen-rich environment.
  • The massive specific surface area of the media.
  • Unrestricted water circulation through the media – no dead spots or anaerobic zones.
  • The media is self-cleaning.
  • The ability to accurately predict how much feed you can use for a given quantity of media.  

Manufacturer trials established that 50 litres of K1 would process the dissolved metabolic wastes arising from 0.75kg of feed (40% protein) per day.   Given that your filtration methods are unlikely to be as effective (nor anywhere as expensive) as those in a modern commercial recirculating aquaculture system, I strongly recommend that you settle on a more conservative number – around 0.4kg per 50 litres of media.

Let’s use this figure to calculate the amount of media needed for a small system:

For the purposes of this example, we’ll assume that we have 100 fish…and we propose to harvest them at 500 grams. That would give us a total fish biomass (at harvest) of 50 kg.  At a rate of 2% (of bodyweight per day), we would be feeding up to one kilogram of feed per day.  Based on my recommendation of  0.4kg of feed/day/50 litres of K1 media, then we’d need 125 litres of K1 media.  This amount could be contained within a 200 litre (55 US gallon) plastic drum.

That level of predictability is the principal benefit of using the moving bed biofiltration process.

The continuous churning movement of the media in the filter causes the tiny elements to rub against each other sloughing off the dead bacteria and continuously exposing fresh habitat for new bacteria.  The great thing about this is an MBBR rarely needs cleaning and, any cleaning that does occur, is limited to draining out any sediment that forms in the base of the filter.

Somewhat paradoxically, I’ll generally use a couple of small 65 litre trickling biofilters to kick start an MBBR.  Using conditioned filters on a new system provides effective nitrification from the outset and will speed up the commisioning of an MBBR quite considerably…but we’ll get into the detail of that when we get to the chapter on starting up a new system.

To summarise, gaining a thorough understanding of how biological and mechanical filters work – and how to use them – is essential if you are going to optimise water quality and fish health.

Each of these mechanical and biological filtration methods performs a similar function – to capture solids from the water column.   This list of filters is far from exhaustive.  It’s merely intended to provide you with options that are affordable and within the scope of the average DIY handyperson.

You can buy various off-the-shelf pond filtration devices but those that work well are expensive and the rest are not worth having.

To summarise, I recommend that you equip your system with most effective filtration that you can afford.  At the risk of beating the ease of cleaning thing to death, it’s important because (and I’ll explain the detail of this later in the  book) filters should be cleaned frequently.  Trust me, if you’re going to be doing it often, you want to make it as quick and easy as you can.

Now, you may have heard about an aquaponics method that uses the growing system for filtration.

Does such a method exist?

The short answer is YES. In fact, there are two such ‘closed loop’ methods.

One is the Integrated Aqua-Vegeculture System (iAVs) developed by Dr Mark R McMurtry.  Indeed, iAVs was the precursor to everything that we now know as aquaponics.  McMurtry vigorously asserts that is is not aquaponics…so the discussion of iAVs ends here…except to say, that is an exceptional way to integrate the closed loop production of fish and plants – and is well worthy of consideration by anybody seeking a productive, resilient and sustainable way to produce food.

I said that there were two such ‘closed loop’ methods so, before we embark upon the design and contstruction of a recirculating aquaculture system, we should take a look at the basic flood and drain system.

-o0o-

In the meantime, I invite you to comment…to express any concerns that you may have…and to provide ideas or suggestions that you feel will improve the book – or add value to it.

Foreword

This Foreword is part of The Urban Aquaponics Manual – 4th Edition.

The Urban Aquaponics Manual first saw the light of day in 2007 – the first publication of its type in the world.

I created the 2nd Edition in 2008 and, in 2010; I revised the Manual yet again (3rd Edition) and made it available through a subscription web site – another first.

In 2012, I embarked on this 4th Edition.

I had already done a substantial amount of the work when, in 2014, I made the acquaintance of Dr Mark R McMurtry. In the ensuing couple of months, everything that I thought I knew about integrated aquaculture got turned on its head. (more…)

Getting Started with DIY Food Production

In our Introduction to DIY Food Production, we talked about why we should grow our own food and how to determine how much we’d need…and we introduced you to Microponics – the integration of fish, plants and micro-livestock.

While Microponics is not complex, we want to make your entry into DIY food production even easier so we’ve mapped out a pathway to help you get started…quickly!

Let’s begin with a garden.

Now, just so we’re clear, I’m not talking about the traditional kind of gardening where you labour and sweat…and run up big water bills while you fight weeds and insects for a tiny share of what you grow.

I’m talking about smart gardening…which is the reverse of traditional gardening.

The methods that we’ll show you are efficient in their use of water and labour…and require no herbicides and pesticides…so the outcome is clean fresh food for you and your family.

We’ll start this gardening adventure with three ideas for you to consider:

Any one of these methods will see you eating your first leaf salad, Asian greens and radishes within a few short weeks of planting your seeds or seedlings.  They will also accommodate any plant – including vines and root crops.

What’s more, they are water-efficient and won’t leave you with a sore back…and will only require the investment of an hour or two of your time to get started.  They will only require a few minutes of maintenance each day.

The other good thing is that you can take a modular approach – gradually growing your vegetable garden – one module at a time.

Right from the outset, we’d encourage you to start to think about food production from a waste transformation perspective.  

At this early stage, that means composting your kitchen wastes and newly acquired vegetable residues.  Keep it simple.  Just put the food scraps into a compost bin and allow them to decompose naturally.  Once you fill the bin, remove all of the earthy-smelling black compost to use on your plants.  Put the partly composted stuff back into the bin and resume adding your kitchen wastes.

You can also get a worm farm going.  Compost and worm castings are superb plant foods…but, even more importantly, they are part of the biological leveraging that enables you to produce your food cost-effectively…while also keeping you out of the destructive and expensive chemical fertiliser/herbicide/pesticide cycle upon which industrial farming is premised.

Once you’ve got your vegetable garden happening, it’s time to expand the menu to include some eggs.

Three chickens will produce 15 – 20 of the cleanest and freshest eggs that you’ll ever eat – each week – and you’ve achieved your first important milestone in your DIY food production.  You can now sit down to your first totally homegrown meals.

Don’t have the space…or local government or housing convenants prohibit keeping chickens?

Never mind…because you will almost certainly have the space to keep Japanese quail.  A dozen quail hens will provide you with 60 – 80 eggs a week.   Five quail eggs equal one chicken egg and, anything that you can do with a chicken egg, you can do with quail eggs.  A few quail hens can be housed in a square metre and they can be explained away (to anyone who needs to know) as cage bird pets.

The arrival of your chickens or quail signals the need for a subtle shift in our waste transformation efforts.  

First, we now need to redirect everything in the way of food wastes to the chickens or quail.  Start to think of those fruit and vegetable peelings, plate scrapings, stale bread and virtually anything that you’d eat yourself as being leftovers to be consumed by your birds.   

Kitchen wastes will offset the cost of purchased chicken mash or pellets and the best (and fastest) way to compost anything is to put it through the guts of a chicken.

Second, we need to start thinking of chicken or quail manure as an asset…something that has value  -and that can have further value added to it.  

At the very least, we can rake it up, mix it up with other carbon-rich plant wastes and end up with a richer compost…or we can feed to worms.  If we are keeping a  dozen or more chickens, then we can gather it up and feed it to Black soldier fly larvae and, in the process, produce another valuable dietary supplement for our chickens.  What’s more, we can take the larvicast (the stuff that’s left over when the BSF larvae are finished with the chicken/quail manure) and feed that to our worms, too.

Welcome to the world of the cascading returns that become possible through waste transformation farming.

Now, we’ll quickly reach the point where…as good as it is…our egg salad will become a little boring from a culinary perspective.  When (and if) you reach that point, it’s time to start thinking about some homegrown meat.

There are a range of options available to you when it comes to backyard meat production and they include:

You can even add lesser known organisms like snails and guinea pigs to the list – subject to your culinary and cultural preferences.

If you already have quail hens all you need to do is buy some cockerels and let nature take its course.  Incubate the eggs and 16 – 17 days later you’ll have your first chicks.  About six weeks later, you’ll be eating your first meal that includes homegrown meat.

You can purchase day-old broiler chicks from a hatchery or feed and grain store and be eating them about six weeks later.

Muscovy ducks are perfect waterfowl for backyard food producers.  They make very little noise and a drake and three or four ducks will keep you in duck meat forever.

A buck rabbit and 4 does will provide you with some of the finest meat that ever graced a kitchen – and you can raise it in a footprint of about three square metres.

Of course, all of this has to acknowledge that meat production is not a story with a happy ending…but, if you already eat meat, then you owe it to yourself and your family to only eat clean fresh meat that is ethically raised…and processed.

Once again, the rabbit manure is an important part of the value chain and should be harvested.  It, too, can be fed to the BSF larvae and/or worms. Indeed, chickens will even eat it.

By now, you are eating clean fresh food the like of which would cost you a lot of money if you had to buy it.

But, we’re not finished.  How would you like to add fish to the menu?

A simple recirculating aquaculture system (RAS) will enable you to grow your freshwater fish in a footprint of as little as five or six square metres.  

What’s more, you can use the nutrient-rich water from your RAS to water your gardens…effectively providing you with two crops – fish and plants – for the same amount of water that it would previously have required just to grow the plants.

Connect a hydroponic growing system to your recirculating aquaculture system and you’re doing aquaponics.

You can even build my personal favourite – the integrated aqua-vegeculture system (iAVs) –  the truly remarkable food production system that was the precursor to aquaponics.

Small-scale food production doesn’t end there.  If you have the space and zoning, you can also include pigs, goats and small cattle in your integrated food production system…along with fungi and fodder plants.  The sky’s the limit!

All of these things are not only possible but they are also quite easy to do…and we can help you.

Welcome to the world of Microponics and waste transformation farming…where the waste products of one organism become the feedstock for other organisms…in the quest for clean fresh food.

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An Introduction to DIY Food Production.

Growing one’s own food is a key aspect of the ‘Have More For Less‘ concept…and I’ve been doing it for much of the past 40 years.  For the past 12 years, I’ve also had an enduring commitment to integrated agri-aquaculture…and I’ve been writing about it for much of that time.

Suffice to say, I have a substantial body of work on DIY food production to share with you.  To simply dump it in front of you would be a little overwhelming – so I’ve created the following links to enable you to access the material in a structured manner.

I developed a small-scale food production regime that, in 2008, I described as Microponics.  Essentially, Microponics embraces the integrated production of fish, plants and micro-livestock…in an urban backyard.  If this all seems a bit confusing, at this stage, just bear with me and I’ll help you through it.

The first thing to understand is that there’s no need to do everything that I talk about.  If you do nothing more than grow your own salad greens, you’ll be in front.  If, however, you want to make a big difference to your food bill…and your health…the sky’s the limit.

Let’s begin with why we should grow our own food…and then we’ll look at what’s involved in producing enough food for our own kitchen.

If we try to mimic commercial food producers, the food that we grow will be more expensive than food bought from a supermarket.  To eliminate the need for commercial fertilisers, herbicides and pesticides – and to offset the cost of live-stock food – we use something called integration to give us a financial edge while, at the same time, preserving our health and the well-being of the environment.

Now, Microponics is the integration of fish, plants and micro-livestock and it operates on the premise that the one thing that all food organisms have in common with each other is water – so we’ll introduce you to integrated aquaculture in its various forms.

Of course, one consequence of growing fish is that we end up with nutrient-rich water that we can use to grow fruit and vegetables for us – and fodder for our micro-livestock.

When people think of growing plants, things like forks, shovels, hard work and sore backs quickly enters their mind.  There are lots of very interesting ways that you can grow food plants that have nothing to do with hard work so we’ll be exploring things like the Integrated Aqua-Vegeculture System (iAVs), aquaponics, wicking beds, square foot gardens – and much more.

A constant diet of fish and salad would quickly become boring so we’ll also look at backyard egg and meat production…and that’s where the micro-livestock enter the picture.  There’s a long list of those for you to choose from including: 

  • chickens
  • ducks
  • turkeys
  • quail
  • rabbits
  • geese
  • pigeons
  • snails
  • bees 

The links in this article are just a taste of what’s to come as we venture forth into the world of Microponics and integrated backyard food production.

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The Have-More Plan

One evening, in early 1976, I walked into the Third World Bookshop – my favourite book haunt – in Adelaide’s Hindley Street night quarter.

About twenty minutes later, I emerged with a book that was to help chart the course of my life.

Written in 1943, “The Have-More Plan – A Little Land and a Lot of Living” was destined to become one of the classics of the back-to-earth genre.

havemoreplan

In just over 70 pages, authors Ed and Caroline Robinson provided their prescription for “how to make a small cash income into the best and happiest living any family could want.”

The book’s lifestyle promise proved to be an irresistible lure for me…to the point where we embarked on our own quest for self-sufficiency.

In late 1976, my family and I moved from suburban Adelaide onto a neglected 20-acre olive tree farm on the urban fringe.

In the ensuing years, we moved from one rented farmlet to another before buying our own house.  While the addresses changed, the general self-sufficiency idea remained constant.  We aspired to the Robinson’s suggestion of “the best and happiest living any family could want”…and we rode a learning curve like the Big Dipper.

We bred rabbits, goats and various breeds of poultry and waterfowl. We reared broiler chickens and pigs, milked two cows, grew olives and owned a 20hp grey “Fergie” tractor.  These humble beginnings paved the way for my introduction to integrated backyard food production (Microponics).

Wind the clock forward thirty eight years…and The Have More Plan re-entered my life.

The need for information relating to a project led me to my bookcase and, as I shuffled through a box of books, suddenly there it was in my hands – my copy of ”The Have-More Plan.”

I re-read the book three times in the week after its re-discovery.

On the first such occasion, I experienced the same sense of exhilaration that I did when I first read it 38 years ago. I even found myself being drawn into the back-to-earth call to action.

The Have-More Plan is a reflection of its age.   While much of its content is timeless, the book is a social snap-shot of the US middle class in the early 1940’s – complete with beliefs, values and behaviours to match the period.

During the second reading, I paused on the Robinson’s call-to-action – to move to a place in the country.

While being on acreage has its merits, much of what is discussed in the Have-More Plan is no less applicable to an urban backyard.

Most people, it seems, aspire to happiness and it’s my perception that they should be able to do that regardless of their age, ethnicity or financial circumstances…or whether they live in the city or the country.

It was during the third reading, that I realised that, for me, the real legacy of The Have-More Plan is the idea that the pathway to happiness is…self-reliance.  What began as an attempt to underpin our own food self-reliance later branched out into other areas like finance, housing, and transport.

In acknowledgment of the impact that The Have-More Plan has had on my life, I’ve named my island micro-farm…Have-More Farm.

You can obtain a free PDF download of “The Have-More Plan”…HERE.

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HMFL Cornerstones

At the heart of the Have More For Less concept is my belief that happiness is the product of simple living and self-reliance.

My own self-reliance is achieved through:  

  • growing food
  • exploring alternative shelter, energy and transport options
  • designing and making – and mending things
  • trading – selling and bartering

In this post, I provide some detail about those strategies.  In so doing, I’m not suggesting that you should follow an identical path.  This is simply what works for me.

Food

Arguably, one of the most tangible indications that you are serious about self-reliance is the decision to assume control of your own food chain.  

There are a variety of reasons for doing so and, principal among them, is food security….ensuring that you have food when you need it.  Knowing where your food comes from, and what’s in it, is central to your health.  Making intelligent food choices is not only good for you; you’re helping the planet out, too.  By the way, implicit in any discussion of food is acknowledgment of the need for potable water. 

A less tangible (but no less important) benefit of growing food is the self-confidence it invests in you.

If the words ‘grow your own’ inspire thoughts of traditional gardening…with all of its digging, weeding and other hard work – relax!  It doesn’t need to be that way.  There are literally dozens of food production strategies that don’t require a shovel or garden fork.

Of course, there are also ways to access clean fresh food that don’t require you to grow it yourself.  You can buy it directly from others who grow it – and still reap the financial and health benefits.  You can also underpin food security by setting up your own food bank…stockpiling non-perishable essentials as a hedge against hard times.

The important message here is to take control of your food chain.

Shelter – Energy – Transport

Once you’re had something to eat and drink, your next survival requirement is shelter.

Regardless of whether they are buying or renting, keeping a roof over their head is the biggest expense for most people.  Even those who have freehold ownership of their homes will be shelling out substantial amounts of money for insurance, rates, taxes, utilities (like water and sewerage) – and maintenance.

Most people require a loan to buy a house.  Many of them will then spend the next 25 to 35 years paying off that loan.  Known as the ‘mortgage trap’ this process is an issue for two reasons.  Firstly, the sheer amount of life energy that has to be directed to the repayment of housing loans is huge.  Second, is the insidious affect that it has on personal freedom.   All manner of life choices will be made to mitigate against the risk of not being able to pay that mortgage.  

You may have to work in situations that you detest simply because of the captive impact of your mortgage.  It’s no exaggeration to say that, for many people, home ownership means decades of anxious scrutiny of the quarterly central bank interest rate announcements.

My interest in alternative housing is largely driven by the desire to demonstrate that people don’t need to be victims of the mortgage trap.  They don’t even need to subject themselves to the indignity that often accompanies the renting of residential property.  Fortunately, there are many strategies that can be employed to offset the cost of shelter.  They just require a little ‘outside of the box’ thinking.

I treat the whole matter of housing as an adventure…a challenge.  I live in a tiny house – not because I have to – but rather because I enjoy it.  The cost effective provision of providing your own shelter is liberating and no less of a boost for your self-confidence than growing your own food.

Living without electricity is possible but, for most people, not all that practical.  Buying electricity through a power company is increasingly expensive but there are things that you can do to reduce your energy costs.

Transporting one’s goods – and oneself – is also an important (and prospectively expensive) part of conventional living.  For convenience sake, I treat them as part of my housing deliberations.

Suffice to say, at this stage, the exploration of alternative housing, energy and transport is a cornerstone of the Have More For Less concept.

Designing, Making and Mending

The procurement of goods and services costs money but, the more you can do for yourself, the less expensive it gets.

Eating out will cost you more than growing and preparing your own food.  Building your own furniture and making and maintaining your own clothes will also save heaps of cash.

Acquiring practical knowledge and skills not only reduces the cost of living but will also assist you to generate income.

Trading – Buying, Selling and Barter

If you’re like most people, there will be some of life’s essentials that you’ll struggle to provide for yourself and that’s where trading becomes a part of your self-reliance program.  

Trading is business…selling products or services.  People have been doing it for thousands of years and, in its most fundamental form, it’s easy to do, too.  

Long before money existed, people used barter – a system of exchange where good or services are directly exchanged for other goods or services – without using a medium of exchange – like money.

To summarise…HMFL is about growing food, living comfortably, design and making, getting around and selling stuff.  It’s about building an enjoyable and sustainable lifestyle in which time assumes a greater value than money.

In my next post, I’ll reveal how a chance encounter with a little book set me on the path to food self-sufficiency.

I like to share and discuss these ideas with others.  To that end, I invite you to go to www.havemoreforless.com.

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The Pursuit of Happiness

I have an abiding interest in happiness.

Having experienced unhappiness (in many of its various forms), I can state categorically that I much prefer happiness. In fact, its pursuit underpins everything I do.

So, what is it?

Merriam Webster’s Online Dictionary defines happiness as…

…a state of well-being and contentment.

Why is it important?

Well, as it turns out, happiness is apparently what the overwhelming majority of people want from life.

Hundreds of people have attempted to put the concept of happiness into words but, for me, nobody put it more succinctly than Aristotle when he said…

Happiness is the meaning and the purpose of life; the whole aim and end of human existence.

But knowing what it is – and why its important – is one thing. Knowing how to achieve it is a very different thing.

The research that surrounds happiness is apparently abundant and, while the numbers vary slightly from one author to another,  the consensus suggests that it is the result of three things – our genetics (50%), our circumstances (10%) and our intentional activities…the things we do on a day-to-day basis.

While there’s not much that we can do about our genetics, the clear message is that half of the things that determine our happiness are within our span of control.  In other words, it’s up to us!

Even cursory reading of writings on the subject tells us that:

  • Happiness is a personal responsibility. You have to determine what it means for you and you have to bring it about. You cannot rely on anyone or anything else for your contentment and well-being.
  • Happiness should not be postponed. In life, there are no guarantees and so happiness must be viewed as a journey rather than a destination.  Grab it where you can.
  • Happiness requires two things – actions and decisions. It’s not going to happen for the simple act of wishing.
  • Happiness is a skill…and the more you practice it, the better you get at it.

To summarise: Being happy – the state of well-being and contentment – is a worthwhile personal goal.   Indeed, it should be our absolute priority and, since it’s within our grasp, we should be ridding ourselves of anything that stands in our path. Each of us is solely responsible for its definition and execution…and for our own outcomes – and that should happen without delay…every day!

That’s the WHAT of happiness.  While we’ll periodically explore that in greater depth, the real focus of www.garydonaldson.net – is the HOW.

I contend that the pursuit of Happiness – through Simple living and Self-reliance – enables us to Have More For Less. Conversely, Have More For Less is the pursuit of Happiness through Simple Living and Self-reliance.

If you’re interested in what I have to say about happiness, I invite you to visit regularly and, if you’d like to discuss it – and exchange ideas on its attainment – feel free to drop around to the Have More For Less forum.

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