In my previous post, I described the criteria that I apply to the design of an aquaponics system.
Upon reflection, I realised that the post contained an implicit assumption – that the system should actually work.
While this might appear to be a blinding flash of the obvious, the simple fact is that many aquaponics systems are dysfunctional – and most of those that do actually grow fish and plants still fall far short of their productive potential.
The simple explanation for the failure of these systems to function at peak capacity is that they are, quite literally, full of sh*t.
Our latest aquaponics system, The Queenslander is a best practice approach to system design and the culmination of everything we’ve learned about aquaponics.
The standard recirculating aquaponics involves the movement of water from the fish tank to flood and drain grow beds and then back into the fish tank (possibly via a sump tank). This arrangement is simple to build and operate and it works……for a while.
Even cursory reading of my work will reveal my disdain for using grow beds to capture and process solid fish wastes. While science and logical thinking is on my side, aquaponic fundamentalists persist with the myth that grow beds can be used as outhouses without consequence.
Cost effective fish production requires that we grow the fish as quickly as possible and this requires that we feed as much as the fish can efficiently convert. To consistently feed at the optimum rate we need to be able to convert the waste products of that feeding while ensuring that oxygen levels are consistent with the needs of our fish.
While this is relevant to any aquaponic system, it’s particularly critical for small backyard units.
Over several years, I’ve seen some very impressive filtration equipment that will do an excellent job of separating out solids but the devices all had one thing in common – they were expensive. Very often, these filtration systems would cost more than all of the other aquaponics system components put together.
I’d also tested most of the less expensive options, like sedimentation and swirl tanks, clarifiers and trickling bio-filters. While they all worked to some extent, they still demonstrated shortcomings when applied to smaller systems.
Anyway, the challenge that presented itself was to develop a cost effective alternative to the bog-standard (and often deadly) flood and drain aquaponics system.
While I’d like to say that outcome of my countless watery meditations produced a silver bullet, but it simply wouldn’t be the truth.
The simple reality is that designing an aquaponic system that really works is not so much a question of what one uses (because none of it is new) but rather where it gets placed and how it is managed to provide the best outcome.
The Queenslander comprises a fish tank, a sedimentation tank and clarifier, the growing systems, a sump tank and a trickling bio-filter.
While the Queenslander prototype was designed to grow the local species jade perch, it should prove similarly effective with any freshwater species.
The design of the Queenslander focuses on three areas…..component positioning, grow bed management and environmental control. The first two strategies are about managing solids in the system and the third aspect acknowledges that virtually all freshwater species will grow best in a specific temperature range.
Over the next few days, I’ll feature each of the strategies in its own post.