The ballast that came with my new tank only has space for 1 flourescent tube. Currently just a 24'' T8 17W. I am having trouble finding ANYTHING this size that has more than 20W. I have found a few 24'' that were at least in the 6700k spectrum, but still only 17W. The tank is also 21'' high.

I know the wpg rules and I know 17 is not going to cut it no matter what the spectrum especially with the height and no reflector. Anyone ever seen a 24'' tube that had higher wattage?