Hope for the Best but Act for the Worst

My recent hospitalisation achieved two things.  Firstly, it served as a timely intervention for what might otherwise have been a life-threatening situation – and it provided the opportunity to think about things.

Since this is not the first time that Mother Nature has reminded me that she recycles redundant organisms, I viewed my enforced break as an opportunity to pause and reflect on how I was doing in my quest for happiness through simple living and self-reliance.  Given my circumstances (I’m 66 years old and I’ve dodged two bullets), it’s not unreasonable that such reflection eventually settles on the question of time.

To say that one’s own time is finite, is a blinding flash of the obvious.  Much less obvious for most of us, however, is the question of time as it relates to the planet…or, more specifically, the amount of time that the planet can continue to support its most troublesome organism…the human race.

Scientists are divided into two camps on this question.  First, there are those who don’t talk about it out of fear of the professional consequences.  Then there’s the second group…the scientists who believe that human habitation of the planet is at imminent peril.  The only thing that divides this group is not if…but rather when.

At the other end of the apocalyptic spectrum is Guy MacPherson who says that human extinction is likely by around 2030.  Other scientists have a more optimistic outlook.  For example, a History Channel documentary titled “Two Degrees:  The Point of No Return” predicts that the world will start to really feel the effects of climate change by 2052…with the “end of days” happening in around 2117.

Regardless of where you’re placed on the spectrum, there’s no denying that it’s getting hotter and that this will have serious consquences for humanity.

MacPherson’s strategy for dealing with this?

“I recommend living fully. I recommend living with intention. I recommend living urgently, with death in mind. I recommend the pursuit of excellence. I recommend the pursuit of love.”

While I don’t know who’s right in this debate (although the emerging evidence seems to support the “apocalyptic ecologists”) I’m drawn to MacPherson’s strategy for dealing with the crisis.

Even if we assume that he’s wrong about the whole human extinction thing (much less the timing), his prescription is a sound one for humans living in troubled times.

My approach will be to hope for the best while acting for the worst.

-o0o-

 You’re welcome to put your views…and offer suggestions…and you can do this by joining us over at Have More For Less.

Are You Part of the Solution?

The United Nations has stated that, if we are to meet the food needs of the projected population, food production will have to double by 2050.

A formidable task of itself, this goal is further complicated by some serious environment factors including:

  • Desertification
  • Soil Salinity
  • Erosion
  • Water Pollution
  • Aquifer Depletion
  • Drought
  • Climate change
  • Loss of biodiversity

Any one of these poses a serious challenge – but all of them together place the world’s ability to feed itself at serious risk.  

And it’s risk from which no-one is immune.  For those of us who live privileged lifestyles in so-called developed countries, think about how quickly the food disappeared off the supermarket shelves the last time you experienced a power blackout – or a little riot – or some similar disruption to your otherwise cruisy lifestyle.

These are the times when having money is really not much use at all.  In anything other than a 48-hour ripple, inflation (official or unofficial) will quickly see your money lose its value leaving you to pay exhorbitant amounts just to acquire life’s staples. 

The first part of dealing with any problem is to know that it exists.  

So, now you know…and, quite simply, if you’re not taking active steps to mitigate against the risks to the food chain, then you’re part of the problem.

So, where are you on the problem/solution spectrum?  Do you have any ideas for how to turn this mess around?

-o0o-

You’re welcome to put your views…and offer suggestions…and you can do this by joining us over at Have More For Less.

Part 1 – Introduction to the RAS Build

This is “Part 1 – Introduction to the RAS build” of  Chapter 8 of the Urban Aquaponics Manual.

Chapter 8 is where we build the system…and its a big one…so I’ve broken it down into a series of sub-chapters:

  • Part 1 – Introduction to the RAS Build
  • Part 2 – The IBC Fish Tank
  • Part 3 – The Radial Flow Separator
  • Part 4 – The Packed Media Filter
  • Part 5 – The Moving Bed Biofilter
  • Part 6 – The Tricking Biofilter
  • Part 7 – Putting It All Together

In Part 1, I’ll walk you through the water flowpath for our proposed build…and then we’ll look at the tools that I’m going to use.  In Parts 2 to 6, I’ll show you how to build each of the major system components.  In Parts 5 and 6, I present you with a choice…between a moving bed bio-reactor (very effective but at a cost) or a trickling biofilter (still quite good but much cheaper).  In Part 7 – we hook our various components together.

It’s useful to have a clear picture of how our RAS will function so let’s begin by getting a grasp of the water flowpath.  Since the water pump is located in the sump, we’ll start there:

  • The pump starts and moves water from the sump to the IBC fish tank.  The water enters the tank tangentially and imparts a circular motion in the water in the tank.   Solid wastes are pushed outwards to the tank walls and fall to the bottom.  When they reach the bottom, they begin to move toward the centre point at the bottom.
  • The weight of the incoming water displaces water already in the fish tank and forces it up the suction end of the solids lifting outlet…drawing any solids that are within reach of the suction.  The water passes through the fish tank wall and into the radial flow separator (RFS).
  • The incoming water in the RFS is directed upwards into the water deflector which causes it to change direction – downwards.  The downward movement of the water encourages the heavier particles (sedimentary solids) to gravitate to the bottom of the RFS.  The lighter water (without the sedimentary solids) rises up to the weir where it overflows and drains into the packed media filter (PMF).
  • As it enters the PMF, the water is directed to the bottom of the filter.  As it reaches the bottom, the velocity of the water is reduced and it moves upwards.  It rises slowly up through the static media in the PMF exposing suspended solids in the water to the sticky biofilms on the media.  The ‘clean’ water overflows the weir and enters the moving bed bio-reactor (MBBR).
  • The water is directed to the bottom of the MMBR slowly rising up and exposing the dissolved solids to the nitrifying bacteria that live on the gently tumbling bio-media. Once it reaches the surface, the water overflows the weir and drains into the sump tank…and so on – ad finitum.

I should point out, at ths stage, that there’s another layout option…one where the pump is located in the fish tank.  The water passes through the filters and then drains back into the fish tank.  This layout requires that position the filters above the fish tank.  That means that we dig a hole in the ground large enough to accommodate the fish tank…or we put the filters on a platform high enough for them to be able to drain directly back into the fish tank.

The upside to this arrangement is that we no longer need a solids lifting outlet – or a sump tank – so the build is easier.  One downside is that integrating growing systems will be a bit more challenging.  And then there’s the digging part.  My view is that life is too short to spend any of it digging holes that aren’t absolutely necessary.  

The RAS Builder’s Toolkit

Building recirculating aquaculture systems, like our proposed unit, are like every other technical endeavour…may seem daunting to the unitiated but really it comes down to some very fundamental skills:

  • Cut plastic – specifically the plastic bladders of IBC’s.
    • Jigsaw
  • Cut steel – specificically the galvanised steel frame of IBC’s.
    • Hand grinder and ultra thin cutting disks
    • Hacksaw
  • Cut PVC pipe – in the range of 20mm to 90mm (3/4″ – 4″).
    • Mitre saw
    • PVC Hand Cutter
  • Drill holes – specifically those required for the installation of bulkhead fittings and Uniseals.
    • Holesaws
    • Drill and Drill bits

To this list, you can add the following:

  • Tape measure and marker
  • Eye and hearing protection.
  • Screwdrivers
  • Wrenches – or (more specfically) any device that will enable you to grip bulkhead fittings during installation.
  • Deburring tool

Before we start work, here are some other things I’d like you to note:

  • With the odd exception, I’ll be leaving all of the pipe and fittings unglued.  This is a basic recirculating aquaculture system and there will be things that we can do to enhance it…and, should you decide to embrace those enhancements at some later stage, doing so will all be much easier if we haven’t glued every fitting or piece of pipe.  Having said that, unglued pipework is a risky proposition, so we need to demonstrate some commonsense around how we set things up.
  • I’ll be using ball valves to enable us to isolate each major component.  This allows us to work on a single component without having to drain the entire system.
  • Each of the filters will be fitted with a dump valve…to enable us to clean and drain it.

That said, let’s build a fish tank.

-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. 

Note:  Registration spammers have found the site so I’ve decided to close off comments here for now.  You can leave your contribution at the Facebook group that led you here…or you are welcome to comment on my Have More For Less forum.

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Part 2 – IBC Fish Tank

This is Part 1 of Chapter 8 of the Urban Aquaponics Manual.

“An intermediate bulk container, IBC tote, or pallet tank, is a reusable industrial container designed for the transport and storage of bulk liquid and granulated substances, such as chemicals, food ingredients, solvents, pharmaceuticals, etc.”

So sayeth Wikipedia.

Notwithstanding the uncomplimentary things that I had to say about IBC’s in earlier chapters, I do acknowledge that, for many people, they are the most cost-effective means by which to acquire a fish tank.  For that reason, we’re going to use one for this build.

My biggest issue with them is that their shape and structure can be problematic when it comes to concentrating and removing solid wastes.  Most of them are not actually square; they’re slightly rectangular.  The bottom of an IBC is not flat; it has structural moulding that discriminates against herding all of the solids into its centre.

Suffice to say, if we can make this work, you’ll be able to take what you learn and make any round or square tank work even better.

Our first task is to remove the steel retaining bars to give us free access to the plastic bladder.

Then, we mark up the top in readiness for cutting.  Removal of the top allows access to all internal surfaces of the IBC – to give it a thorough cleaning – and for ongoing management.  

This particular unit contained glycerine in its former life – non-toxic, water-soluble and easy to remove.

An electric jigsaw is my weapon of choice when it comes to cutting IBCs and other plastic containers.

The dump valve enables the IBC to be emptied and the space immediately behind the valve is a trap for solid wastes.  To prevent your toddler (or your sister’s toddler) from operating the valve, we’re going to zip tie it in the shut position.  And then we’ll plug up that space behind the valve to prevent solid wastes from accumulating there.

I’d like to be able to drain this tank directly through its bottom but, the pallet arrangement doesn’t easily lend itself to that, so I’ll install a solids lifting outlet (SLO).  This is a fancy name for a simple device that uses the weight of incoming water to displace water already in the tank…forcing it up a pipe and out of the tank.

Clear as mud…right?  Well, hopefully, this simple diagram will clarify things for you.

We’ll be setting this IBC up so that the solid wastes are directed to the centre of its bottom…so it’s logical that we’ll place the suction end of the SLO over that point.

Before we get too concerned about the SLO, however, it’s time to modify our IBC for its new role as a fish tank.

Step 1 – Remove the retaining bars at the top of the tank.

Image

Step 2 – Mark out a square section to be removed to provide our tank opening.

Image

Step 3 – Cut and remove the plastic top to create the opening.

Image

 Step 4 – Mark out the exit point for the SLO – and drill a hole of the appropriate size.

There are two way that I’d propose for the

Step 5 –

 

Building the SLO is a simple matter of assembling some PVC fittings and a couple of short sections of pipe.

-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. 

Selecting the Components

This is Chapter 7 of the Urban Aquaponics Manual.

In the last chapter, we developed a design specification for a small recirculating aquaculture system (RAS).  Now. it’s time to select the components that we’ll need for the build.

Before we go too much further, I need to say that I don’t propose to provide a set of plans or a materials list for the design that we’ve produced.  Just accommodating the measurement system differences from one country to another makes such an undertaking a nightmare.  

Ultimately, you’ll make component choices based on…

  • the amount of fish that you want/need to produce
  • what’s available to you in the way of materials and equipment
  • the amount of money that you have to spend
  • your abilities and skills
  • your personal preferences

…so, I believe that it’s more important that I provide you with options that can accommodate your specific circumstances.  

We’ve all heard the old adage…”If you give a man a fish, you feed him for a day.  If you teach a man to fish, you feed him for a lifetime.”  

My goal, by the time you ingest the contents of this Manual, is that you should be able to take the principles that I describe and apply them to the broad question of system design rather than just be able to build one specific system.

Our goal is to produce clean, fresh food…so the materials from which our components are made – and any prior use that they may have had…must be safe for humans and fish.  Reject any tank or vessel where you can’t be certain of what it contained before it became available to you.  

At this stage, we’re just looking at components.  While, for the purposes of illustration, I’ve approached the design process in a linear fashion, I recommend that you read the entire manual before you start to get too set on your design.   Our basic design is just that…basic!  There are plenty of things that we can do to enhance the basic design and I want you to have the opportunity to consider those tweaks and bells ‘n’ whistles before you finalise your plan.

That said, let’s commence our component search.

Tanks

The key imperative of a fish tank is its ability to facilitate the removal of solid wastes.

Concentrating solids within reach of the drain is the consequence of tank shape and design…and managing water movement within the fish tank.

The ideal fish tank is robust, round in shape and will have a slightly sloping bottom with a centre drain at its lowest point.

Water returning to a round fish tank is directed tangentially at the surface.  This creates a ‘hydrocyclone effect’ – setting up a slow circular movement in the water in the tank.  A weak centrifugal force causes heavy matter in the water (solid wastes) to move outward to the wall of the tank and to slowly spiral down to its bottom eventually moving across the tank bottom toward the drain.  

You can replicate this effect – on a tiny scale – by swirling the last mouthful in a tea cup while observing the dregs gathering in the centre of the bottom of the cup.

Most smaller purpose-built aquaculture tanks function like this. 

They are also usually quite expensive.  Secondhand units may become available but, you’ll need to act quickly since they are usually in high demand from aspiring small fish farmers.

Other off-the-shelf options (in order of preference) include:

  • round plastic or fibreglass tanks with flat bottoms…like re-purposed rainwater tanks or large round livestock watering troughs.
  • square plastic or fibreglass tanks…(preferably with rounded corners) like produce bins.

The desirable circular movement to which I referred earlier can be created in round tanks with flat bottoms – and even square tanks – and we’ll cover that in more detail as we get into the construction of our system.

Rectangular tanks are the most difficult to accommodate as fish tanks so I’d recommend that you avoid them if at all possible.

While I prefer those made of food-grade, high-density polyethylene or fibreglass, people have managed to repurpose all manner of containers for use as fish tanks.

DIY Fish Tanks

So long as we bear in mind the need to concentrate solid wastes so that they can be removed from the fish tank, the scope for viable do-it-yourself fish tank options is limited only by your imagination.  

This situation is made possible by the existence of the food-grade low density polyethylene liner.  LDPE liners are tough but flexible and can be used to line fish tanka that are built inground, on the ground and above ground.

They can be used in conjuction with existing concrete, steel/aluminium or brick/masonry structures – and you can build very serviceable fish tanks from timber and/or plywood and line them to make them waterproof.

Intermediate Bulk Containers

IBC’s are plastic vessels (generally with a capacity of 1000 litres or 250 US gallons) contained within a galvanised steel frame with a pallet base.

Notwithstanding that they are probably the most widely used off-the-shelf fish tank option in the world, I’m not a fan of IBC fish tanks – for the following reasons:

  • Encouraging a circular flow in an IBC can be difficult and that can negatively impact solids removal.
  • They are not fully UV-stabilised and will begin to fall apart over time.
  • It’s hard to know what has been stored in them. They are often used as mixing tanks for herbicides and pesticides.
  • They will always look like IBC’s.

Regardless of what I say, some of you will opt to use them anyway – so, if you’re certain about their previous use and they are really cheap, I’ll do what I can to help you to address their shortcomings later in the manual.  We may even experiment with putting a bit of ‘lipstick on the pig’ to make it look a little less aesthetically confronting.

Mechanical and Biological Filters

I’ve built filters out of all manner of off-the-shelf and recycled containers.  Some worked better than others.  The ones that I liked the most just happened to be those that were the easiest to clean.

Not surprisingly, those that were usually the easiest to clean usually worked best…largely because a clean filter works better than a dirty one.

With the exception of swirl separators, which must be round, shape doesn’t matter too much.  Having said that, I have a preference for round filter tanks mainly because they are readily available in a variety of sizes and they’re relatively inexpensive.

And, at the top of the list for cost and availability, is the ubiquitous recycled blue plastic barrel.  

These two barrels are 130 litre (30 US gallons) – perfect for our emerging RAS design.

Indeed, the only drawback of these robust vessels is the colour.  That can be addressed by buying new plastic barrels (available in a range of colours at four times the price of recycled ones) – or by cladding them in something a bit more aesthetically pleasing.

Water Pumps

Water pumps are the means by which we recirculate the water through our RAS.

For our purposes, they tend to be of two main types – submersible pond pumps or externally mounted centrifugal pumps. 

Pond pumps are cheap, very convenient to use, require minimal plumbing and are suitable for most urban aquaponics applications. The principal limitation of pond pumps is that they are best suited to low head applications. Flow rates will diminish quickly once the pumping head increases.

Two sumbersible pumps of the type commonly used by backyard fish farmers. The unit on the left is designed to be used as a submersible but also as an externally mounted pump if required.

Externally-mounted pumps generally cost more to buy but usually move more water for a given power consumption – and they are better suited to applications where the water has to be pumped up heights of greater than a metre. Their installation is also a bit more complicated.

An externally-mounted centrifugal pump – available in various sizes and usually reliable and long-lived.

A Few Pump Hints and Tips

  • Depending on your application, it may pay to consider using two small pumps rather than one larger one. The benefit of multiple pumps is that, if one pump fails, the other will keep your system going long enough for you to discover the problem. This is simple risk management.
  • Avoid the use of submersible sump pumps – they are generally not rated for continuous operation – and they can be power-hungry.
  • It may pay to buy more pumping capacity than you need initially – to cater for the likelihood that you’ll expand your system.
  • While independence from the electricity grid is a worthwhile goal, solar-powered pumps add a new layer of complexity to the establishment of an urban aquaponics system. Keep it simple to start with. 240-volt (or 110-volt for US readers) pumps will provide for relatively reliable and inexpensive recirculation during your formative stages as an urban fish farmer.

Air Pumps or Blowers

I regard air pumps as essential equipment because low dissolved oxygen levels are the principal cause of fish deaths in small aquaponics systems. In any case, fish, plants and nitrifying bacteria all benefit from high dissolved oxygen levels.

In the event of water pump failure, good supplementary aeration may be the difference between a minor nuisance and a disaster. Air pumps are cheap insurance.

Our little system is going to require aeration at several points:

  • Fish tank – continuous
  • Moving bed biofilter – continuous
  • Packed media filter – periodic…when cleaning
  • Plant growing system – continuous

We can have one larger air pump that meets all of these requirements – or we can have two (or more) air pumps to deal with specific parts of the system.  Air pumps (particularly those with diaphragms) can fail at short notice so having a couple of smaller air pumps might be a useful risk management strategy.

Pipe and Fittings

PVC pipe in the range of 25mm – 50mm (1″ – 2″) is widely used for backyard fish farming and is easy to work with.  PVC pipe and fittings in our preferred size range are of two main types…pressure and drainage.  The types are not compatible with each other although experimentation (and the judicious application of heat) will enable you to reconcile the types where circumstances demand it.

PVC fittings come in wide range of sizes and types. Their cost quickly mounts up so limiting to them those necessary is a good idea. Having said that, most backyard fish farmers have a substantial collection of PVC fittings…”just in case…”

We’ll be using 25mm (1″) PVC pressure pipe and fittings for the water supply side of our little system and 50mm (2″) for all drainage pipework.  

Some people like to use larger stormwater pipes and fittings on the drainage side but I’ve found that the lower water velocity of 90mm+ pipework often allows solids to settle out in the pipes – with the potential to create anaerobic zones.

Control valves may be required in some situations and the two most common types in use are ball valves and slide valves.  Ball valves are available from the same places that stock the PVC pipe and fittings.  Slide valves are nicer to use, more expensive to buy and are usually only available from specialty aquarium/aquaculture suppliers.

Connecting Tanks and Pipes

Secure connections of pipes to tanks are achieved through the use of bulkhead fittings (also known as tank outlets) Uniseals and flange fittings.  Each of these has their place in RAS construction and we’ll learn more about them in the next chapter as we begin the build.

One of the challenges with this chapter, was deciding what to leave out (rather than what to include).  The list of gadgets that can be included in a small-scale RAS is long.  What we’ve covered here will allow you to build a RAS that is productive, resilient and versatile.  You can always reflect on the available bells ‘n’ whistles later – as you sit down to eat your first fish and salads.

In the meantime, I propose to build our little 1,000 litre system using the following:

  • IBC – not because I like them but because (regardless of what I say) some of you are going to use them. 
  • Blue barrels – I’ll use three of them to create a radial flow filter, a packed media filter and a moving bed biofilter.
  • PVC pipe and fittings – we’ll use 25mm (1″) for the pressure pipework and 50mm (2″) for the drainage.
  • Pump – 4500 litre submersible pond pump.
  • Bulkhead fittings, Uniseals and flange fittings – to hook it all together.

-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. 

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