Hi, I have a zoo med dual light kit and I bought two 100W UVA light bulbs. What is the normal life of these bulbs? They are a bit pricey and noticed that they only last a couple weeks or up to a month or two and they burn out. What kind of light bulbs do you guys use? I only have 1 turned at a time, once one burns out, i turn on the other one. Any bulbs you guys can recommend to me would be greatly appreciated!