I ran 2 ushio 10K 175W over my 45 breeder. PLENTY of light; depends on what you want to keep, but the single 175 you have should do pretty well. I'd really consider using an ushio rather than XM if you're running a single bulb. The color on XMs is nicer, but you'll get alot more intensity with an ushio. I saw this over Troy's tank recently, he has an XM on one side and an Ushio on the other.