I got my T8 with the light fixture option, and the bulb that came with it burned out pretty soon after it started being used. Must have just been a bad one. I got a replacement from Wal-Mart, but I'm seeing that it is putting off enough heat to gradually raise my ambient temps throughout the day, so that by lights-out at night it can actually be starting to get too warm. And then I have to adjust my real heating equipment for night time, since without the light on the cage can get down to 75 or below, if I don't compensate for not having it on. So my question is what bulb do you use that doesn't affect the ambient temps, so that I can keep it stable from day to night without adjusting things twice in every 24 hours to compensate for the bulb's heat?