I have a similar setup in my basement for winter growing. I used an IBC bottom 24" deep, placed a 1" styrofoam hinged top on it and a 2'x4' grow bed mainly to filter the water. Initially I intended to use it as a backup just in case something happened to my main tank in the greenhouse and I wouldn't loose all my fish. Now I just grow lettuce and do different experiments. Your grow box with the net cups may not work because the fish will eat the roots.