If you do not know what is iAVS, then check these two videos. The first one shows the simplest setup:
The second one shows how Murray Hallam is using iAVS:
This is amazing!
Aubrey I checked the two sets running in your greenhouse. It is indeed a wonderful and simple system. Wish I knew this before I tried the aquaponics that everyone is doing!
Indeed, Gary maintains a facebook for iAVS. Here is the link, he calls it iAVS Sandgardening:
You can learn a lot there if you want to do iAVS.