Aquaponics, Food for a Hungry World

Aquaponics, Food for a Hungry World - I spend a lot of time thinking about this, although I won't be doing anything physical on it until next year. I am not writing this blog for anyone else - just me! I don't mind if no one else reads it at all, but it helps me to keep a record of my progress and my thinking.

But if you do decide to read it, feel free to comment!

Sunday, 26 June 2011

Breeder Colonies

I have been reading about a breeder colony: in other words a separate tank in which to breed new fish. The website where I found the information, Tilapia Farming At Home, is a US based website, and the suggestion is that by producing hybrids from a male O. Hornorum and about half a dozen O. Mossambica females, you produce 98% male offspring, thus avoiding the problem of over-breeding in the fish tank. In this website, photographs indicate that the offspring are a reasonable size and shape!

I need to get a second and third opinion about this, as well as checking availability of these varieties of Tilapia - but it sounds like a plan!

Monday, 20 June 2011

System Design

I've been thinking a lot about how to design a system in a 4m x 3M Keder house. I am coming around to the idea from Murray Hallam, that perhaps a sump is a good idea, mainly from the point of view of relative levels. The fish tank could sit on the ground, and the grow beds could be fairly low (which I would prefer, for access to climbing plants) especially if the sump was sunk into the ground. It could be completely insulated to help maintain temperature, and the growbeds could be insulated too. Another plus is that much of the pipework could be run underground, which, especially if lagged, would also help to retain temperature.

I needed to find out how big the sump needs to be, so I asked Charlie Price about the medium/water ratio in a grow bed. (He said it's about 2/3 to 1/3) I have worked out that if I have five bath-tub growbeds, I would need a sump with a capacity of around 450 litres.

I have asked Murray Hallam if I would be able to use the sump as a breeder tank - which could solve the fish stock problems. I read that you can have a breeder tank for Tilapia, and if you have a male of one type (specified) and I think five females of a different type (specified), the offspring are 98% male, and it occurred to me that these could live in the sump!

Now I have to find a source for a 500 litre tank of the right shape, preferably without buying two IBCs!

Thursday, 16 June 2011

How Safe is Aquaponics?

The recent e-coli scare in Europe (the scare, but not the infection, has spread to the USA) has pointed up the question of safety in vegetables.

Over a couple of years, in the States, a comparison between green vegetables purchased in grocery stores, and those grown aquaponically, showed that the latter were pathogen free – in other words, the aquaponically grown vegetables were 100% safe.

However, ironically, again in the USA, aquaponically grown food cannot qualify for a Food Safety Certificate. The reason for this is the book of rules, and specifically two parameters which cannot be complied with. The disqualifications arise because of the presence, first, of animals in the growing area, and second, of untreated manure in the growing area. The book of rules does not take into account the fact that manure from cold blooded animals cannot transmit these diseases.

In the UK we have the Soil Association, and here we come across a similar contradiction – food cannot be considered organic if it is not grown directly in, and harvested from, the soil. And yet most of us are aware of organic farmers who would not eat their own produce, because of the pesticides they are allowed to use, and which would certainly kill the fish!

Is it time to re-evaluate? Well, I guess that’s up to the Soil Association. But I confess to feeling that the current definition of ‘organic’ is out of date and therefore lacks credibility. If you are growing in soil, you can gain organic certification without improving the nutritional value of your produce, depending on how you treat your soil; and of course it does not preclude the possibility that the produce could transmit e-coli. If you are growing aquaponically, you cannot do anything which might damage your fish, and if the fish survive, I reckon I will too!

So I feel enthusiastic about the proposed Aquaponics Association in the USA, whose purpose will be to 'preach the gospel' of aquaponics and perhaps persuade the certification bodies to adjust their criteria. Of course, the US, particularly Hawaii, and Australia, are way ahead of the British in the field of aquaponics - but we must do our best to catch up.