Originally Posted by Ami
The hoods only have place for one 18" tube each. The kits came with the hoods. The top of the tank is designed so that one can only fit two hoods.
I would have to say that this is going to be less than adequate on a 4-foot tank. Low-light plants might make it, but I would not expect moderate light plants to last, and that limits your selection of plants quite a bit.
If you stay with what light you have, Anubias will manage; probably Java Fern, and Java Moss on wood. The Aponogeton I doubt, nor the Onion plant. Lily need more light; I have a couple red Tiger Lotus and they just manage with my moderate light. I had them in the 33g with one 20w tube, but after I moved them into the 90g with two 40w tubes, they have shown remarkable growth by comparison.
If you want to increase the light, my suggestion would be a glass cover (you can buy these to fit standard aquarium, the front part hinges back on some or slides back for feeding) and a light fixture that then sits on the frame (the glass cover unit sits down on the lip around the inside of the frame). A single T8 48-inch would work, or a T5 single tube, or even a dual T8.