Archive for the ‘aquaponics’ Category

About two years ago, before I had heard of Permaculture, I had been exploring the idea of closed systems. The main reason for this was what would be the ideal situation to be in, living-wise, in the event of an Event. What I mean is that the worst thing you can imagine has happened, but as far as you are concerned you can just carry on, business as normal, because you are already living your life in such a way that you are impacted minimally if at all.

I had sat down with a program called GraphViz which is a free, open source, brilliant tool for creating graphs of systems. These are mathematical graphs, not the type that you make in excel. A simple and incomplete example might be:

I was trying to and create a model of a self-sustaining system. My ideal farm would have all of the elements needed to sustain itself from within (OK, with the addition of sunlight and water). Each subsystem (rabbits above) would have its needs provided by other subsystems and in turn would provide for others.

The first example of a closed system I had come across was the Chinampa systems used by the MesoAmericans. These are a mixed aqua- and agra-culture system. The main ingredients are chickens and fish. The fish live in a canal system which also holds large raised beds. The raised beds were usually about 30m long by 3m wide and the canals inbetween were shallow and about the same dimensions. The chickens were used for eggs and meat, but their manure was put into the canal system to encourage an algae bloom, which would feed the fish. These fish were used for food, but also their waste enriched the sediment at the bottom of the canals. Periodically this was placed onto the raised beds which were used for growing vegetables. The canals were also used as a heat sink to keep the temperature of the beds a little higher to give a longer growing season.

Once the vegetables were harvested the waste products were put into a vermiculture system to compost. This was put back onto the raised beds (along with human manure) but the worms were used to feed the chickens, thus closing the system. I drew this system out as:

When these chinampas were being used they provided a vast amount of food which sustained the (then) large population. When the Conquistadors arrived they promptly put in ‘proper’ farming systems and the population crashed, although this was probably more to do with metal than food.

I have about a dozen of these elements which fit together into the most horrifically detailed graph. Each individual element is nice and concise, but the effect of putting them al together is almost unreadable, which shows I need to improve my GraphViz skills. I also need to include more elements as my initial attempts were a little naive, but you live and learn.

The reason for explaining that is so that you can imagine how utterly pleased I was when I watched the delightful Geoff Lawton‘s Introduction to Permaculture and saw the following:

One of the ideas in Permaculture is that there are no such things as waste products – only that elements require inputs, have characteristics and product outputs. An over-abundance of any particular output can be viewed as pollution, or as a sign of a badly designed system.

The DVD is very enjoyable, a gentle but solid introduction to the ethics and processes of Permaculture. I would recommend it to anyone who is interested in finding out more. Alternatively (and on short notice but I only found out about it this morning) if you are anywhere near Cambridge there is an Introduction to Permaculture course being run this weekend by Cambridge Sustainability Centre which looks good. I would love to but cannot attend.

Make-do Aquaponics

Posted: June 20, 2011 in aquaponics

I would really, really like to set up an aquaponics system  at my house but, for various reasons I am currently unable to.

To cheer myself up I decided to have some fun this week. We haven’t cleaned out the fish tank for an horrifically long time. The water looked like it was going to get up and walk out on us. The fish seemed happy though. Given that the house has just been put on the market and a green slime-filled fish tank doesn’t exactly shout “Buy me” it was time to give it a clean.

The gravel layer of the tank was full of fish poo. I decanted the first 10 muck-filled litres into some bottles that I’ve have lying around and distributed the high nitrogen filth around the garden.

It has been a few days now and so far nothing has died. The courgettes are looking particularly lovely.

In a full-blown aquaponics system the fish waste water is fed into a hydroponics setup. This cleans the water for the fish and provides nutrients for the plants, making everyone happy. You get lovely vegetables and the freshest fish you can imagine. One day I will get one setup but at the moment the plants will have to make do with the stinky fish water.