And of course, you can scale this up with multiple trays and fish tanks, you can connect them in series so one set of fish provides for another bed of plants down the line, and you can also scale up the size of the fish tanks and the plant containers. The only thing I don’t see addressed in the diagram is the aeration of the water for the fish tanks to make sure they get enough oxygen, but adding one or two aquarium pumps wouldn’t pose too much of a technical or financial burden. It might also be possible to use the agitation of water by the addition of other water to a tank as a means of oxygenation, especially if the tank and the input / output system was big enough.