A piece of coarse screen
(2.54 cm mesh) was secured 20 cm below the polyethylene raft to
prevent the plant root from possible disturbance by the fish. Each
tank was encased in a 200-cm tall wooden framework, which a
timer, a feeder and an illumination device could be fixed onto. A
near-sunlight 28-W 115-cm T5 tube was used for illumination,
hanging 25 cm above plant top and its height was adjusted as the plant grew. Top and sides of the framework were covered with
black vinyl to obstruct the interference of illumination from
outside.