is this a 15 long tank?
If so, I I believe back when I was into saltwater I actually was able to cram into a hood I made for one witth I believe 90 watts of lights.. All regular flourescents.
You can use the fixtures they use for reptile bulbs, just not the builbs I believe.. Which means you can mount a row of those fixtures (or simliar) and put the correct bulbs, I used the 'blue' bulbs and white actinic.
Overall I think it worked quite nicely, the hood was simple.. made out of 1/2" ply, just a box that fit on the tank.. I staind it as well. They worked great, and wasnt' hard to build!
15 gallon tank 1 yr old ran by a 15 yr old!