So while we’re waiting for our bacteria to arrive, there are a few other things that we’re keen to sort out with our home aquaponics system! We’ve got a 400 - 500 litre tank of food grade plastic full of water, and three gravel bedsof about 60L each stacked on milkcrates right next to the tank. The water is running smoothly from the tank into the gravel beds, and draining away quite nicely. In the beds we have some small seedlings growing - they aren’t in full sunlight though and could probably do with a few more good Bondi rays. We have no fish in the tank - we do have Seasol, a liquid seaweed concentrate in the water though, to help our fledgling plants along.
The gravel beds are about 30cm deep and their total volume is around 180L Here is a picture of our small aquaponics system. We actaully have three grow beds now. (Don’t know what aquaponics is? Head over here for a quick explanation.)
What we need to do is figure out the ratio of water to gravel beds - Bruno suspects that we are going to need more grow beds for this amount of water. And the amount of water that we need will also tell us how many fish we can have, (which will in turn effect how many plants we should aim to grow to keep the system thriving.) The plan is to buy some perch fingerlings because we’ve heard that they are pretty hardy little things, and ofcourse we have to figure out how big the fish are going to get. In this excellent forum post from backyard aquaponics forum derekh talks about a 2:1 grow bed to tank volume ratio is roughly the ideal. So as we have 3 grow beds with a volume of 180L approximately and a tank of volume 450L (or so), it would seem we need more grow beds! I’m going to head over the forums and see what they think.