Steve, becareful with your bulb selection, you probably have an M57 probe start ballast, so you have to stay with American/chinese bulbs. Stay away from Japanese and German bulbs, they require pulse start ballast. If you know that you have an electronic ballast, disregard what I wrote, and use any bulb. Good luck.
here is a good link of what you can run with which ballast.
http://www.aquarium-lighting-guide.c...al-halide-ansi