Aquaponics: week 3

The aquaponics system by all accounts is going great guns. The fish are getting bigger, as are the lettuces. The tank looks rather nasty as is getting scum buildup (technical term biofilm) and smells a bit pondy, but this is because the water in the tank doesn't get changed and therefore the tank doesn't get cleaned. Despite this, the water is clean and clear which is how it should be - the plants take all the waste out of water (in a process explained below) and so what is being pumped back into the fish is effectively clean (hence no need to change the water or have a filter).

The big boy Pumpkin and two of the triplets havin a chat

I tasted a leaf of the lettuce yesterday and it was good (whilst at the same time ignoring Elliot cracking himself up by saying I just ate fish poo - mature as always).

With growing lettuce leaves comes growing lettuce roots. And they have got massive since we set this all up almost three weeks ago. At that time it was bloody tricky to get the roots down through the bottom because they were so tiny and delicate; now they are huge. These of course hang down out of the bottom of the net pots and sit in the water that goes through the tubes.

The water is tested for pH, ammonia, nitrite and nitrate. The ammonia (from the fish waste) shows up first. When significant quantities of this are present in the system there is a bacteria in nature that will start to grow and feeds on ammonia and converts this to nitrIte. Once nitrIte is present, there is another bacteria in nature that converts nitrIte to nitrAte.  The nitrAte is the good stuff that becomes the fertiliser for the plants. When you get a "fully cycled" system the levels of these three should all be zero - this means that the bacteria that converts ammonia to nitrIte is established and the bacteria that converts the nitrIte to nitrAte is established. This means that the nitrogen cycle is complete and the plants are now supported by the fish.

The ammonia started to show a week or so into the project and the nitrIte showed soon after. We have just started to get nitrAte showing up in the tests as the ammonia and nitrIte are starting to drop (all consistent with the science of aquaponics).

Ammonia, while from the fish's own waste, is not good for them, which is why when keeping fish as pets in a bowl the water needs to be changed regularly. You don't have the same need to do that with aquaponics as the plants and growing media become a filter - all quite clever really.

Testing for ammonia, nitrite and nitrate
(measured in parts per million)

We feed the fish twice a day and test the water every day and the ammonia is now down back towards zero and the nitrite is heading down too. These are all good signs. So, so far, so good. No system breakdowns, no flooded conservatory and no floating fish (rather pleased as am becoming a tad fond of them).

It's basically a mini ecosystem we have here. Because no chemicals are added, this, put simply, is nature. The biofilm, the bacteria, the nitrogen, the fish, their poo, the plants - the whole "circle of life" (well, not really, but I felt an Elton John moment coming on). It's pretty darn cool really.

Oh, and Elliot is heading away for the long weekend doing something silly like camping so it is all in my capable hands!!! I'm sure there will be instructions given, phone calls, texts and photo updates insisted upon.