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Thinking about designing your own backyard Aquaponics system?

 When I sit down to design any backyard food production system, I apply a list of design criteria which includes:

  1. Safety…..all prospective hazards including drowning (particularly for toddlers or pets), electrocution or toxic materials are minimised.
  2. Productivity….the system should be capable of yielding a quantifiable amount of clean fresh produce.
  3. Environmental control – you need to be able to precisely control the production parameters.
  4. Scale – the system needs to be suited to the available space.
  5. Minimal effort – your system needs to be easy to set up and operate.
  6. Versatility…..the system should be expandable and should integrate well with other food production systems.
  7. Affordability – it should be cost effective to set up and inexpensive to operate.
  8. Sustainability – opt for appropriate technology and minimise your use of water, energy, manufactured rations and fertilisers where possible.
  9. Portability – essential for those who rent their homes.
  10. Aesthetics – your system should be neat and tidy.
  11.  Cleanliness – doesn’t produce objectionable odours or attract/house vermin or pests.
  12.  Quiet – the sound of gurgling auto-syphons may be music to your ears but your neighbour may not agree.
  13.  Location – taking account of frequency of contact, solar exposure and availability of power and water.
  14.  Durability – your system and its various components should be able to stand the test of time.
  15.  User Comfort – take account of working reach and heights – minimise lifting and carrying.

When designing backyard aquaponics systems, I take the view that (as EF Schumacher observed) small is beautiful.  I raise fish in tanks of 700 – 2000 litres because I can exercise the sort of control over their environment that allows me to out-produce larger systems where such control is not exercised.

I also like square or rectangular fish tanks because they are easier to insulate and cover (which impacts their productive potential and safety) and they are more efficient in their use of space – an important consideration in an urban backyard. 

Square or rectangular tanks also have the added advantage that they can more readily serve as platforms for other food production systems like bio-filters, grow beds or duckweed tanks.

I dubbed this basic configuration of small square tanks which support bio-filters (or growing systems) the microFish Farm.   This idea has been widely replicated in hundreds of systems throughout Australia.

I have built and operated at least 10 of these these units (in a variety of configurations) in which I’ve grown jade perch, barramundi and Murray cod. 

While these little systems have put plenty of fish on my dinner table they have one important failing.  Like most media-based aquaponics systems they rely on the grow bed media to trap the solids.   In a media-based system, the grow bed often functions as a biological filter, too…..and there’s the problem.  The two functions are at odds with each other.

At the end of the day, the productive capability of any aquaponics system depends on your ability to process ammonia and nitrite and to maximise dissolved oxygen levels.   Aquaponics system design must acknowledge water quality (from the perspective of the fish) as the most important criterion of all.

The next post (titled The Queenslander – an Aquaponics System that Really Works!) will show you how we re-configured the microFish Farm for enhanced productivity and reduced risk.

You can track the progress of The Queenslander project on my forum at  Aquaponics HQ.

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