When changing light bulbs in your aquarium fixture, be sure to allow the lamps plenty of time to cool off before attempting to remove them. Whether T5HO, metal halide, or whatever you like to use, the bulbs operate at a very high temperature and can burn your hands. This may seem like an obvious suggestion, but when people get into aquarium maintenance mode, they may forget the bulbs are hot or may lose track of how much time has passed between turning them off and attempting to handle them. Also, make sure your hands are dry. If you grab a hot bulb with cold, wet hands, the bulbs could shatter. Lastly, when handling metal halide light bulbs, don’t grab the bulb with your bare hands. Because the bulbs run so hot, grease and oils from your hands can cause cracking on the surface. Though it’s probably a rare occurrence, I wouldn’t want to have to replace a $60 bulb because of it cracking.