Bulb replacement recs?

[eds]

I will be replacing my aged existing bulb, and was hoping some of you would share your wisdom in this area.

I have a 30 gal. The All-glass light that came with it has a single 24" bulb. The fixture says 120v, 20w, 60hz.

It has a GE Aqua Rays 25w bulb, and a 25w condensor. I'm a little surprised that the light came with a bulb with a higher wattage rating than the fixture states.

Are there any bulbs out there that would allow me to improve my lighting? Are there any higher wattage 24" bulbs out there? The stores I checked yesterday (LFS and Pet Supplies) had only 20-25w. Will probably make a trip to the BORG this weekend.

I saw some fixtures that have 30w 36" bulbs, but they are around $70. And the 2-bulb fixtures would require that I also buy a new cover becasue they are deeper - front to back - than will fit on my current cover.

I guess I'll eventually end up going one of these 2 routes. Not sure what the total wattage was on the 2-bulb fixtures. But at present, I'd rather just replace my bulb. Any suggestions?