i only use household bulbs. First off they last much longer than petstore ones. Second i am also able to get all my temps up to the exact i need with no problems..as invictus said they are sometimes too hot and i need to raise the fixture or reduce the wattage of the bulb. I find them great. I had the petstore ones and in like a month the threaded part that goes into the fixture always detaches from the bulb because it gets very hot. But with these bulbs i only have to change them once in a while.