Since it needs a nitrogen rich envirornment, you might want to throw some goldfish or something in there. I was going to use the waste water from my water changes I do every month on my fish tank. But three 55 gallon tanks, that is a nice gift!!! Good luck!Great idea. I had a friend give me three 55 gallon fish tanks in which I was going to do aquaponics never got to that. So I'll set them up and grab some duckweed out of the pond and get it started.