I am having pretty good luck just floating a big hunk of Styrofoam with holes cut in it for the jiffy pellets that have the lettuce in it, right on top of my gold fish tank, it only has an air rock in it, no filter and while I am getting a bit of algae due to the light(now I see why you have the bins) we have had three big salads from it and I have been sneaking a few leaves here and there for sandwiches and just to taste! There are only 7 plants but they do seem to like the fish poo water.
I think I will try a small tray on top next time with a small pump to pump the water up and make a bell siphon to drain it back into the gold fish.