Ok, I finally switched one of my girls over to a uth, and done away with the heat lamp. I have the thermometer probe stuck to the underside of the tank in between the uth and glass. It's staying right around 85*, my question is I've read on here something about a thermostat to regulate the temperature, but I didn't see any today at petsmart, so my question is, do I really need one? Especially since the temps seem to be sticking in a good range or do I really need one? If so please give me some recommendations. Thanks!