I have three thermometers, one on the hot side, one on the cold, and one in the middle along with a hygrometer to check the humidity. I don't have a thermostat for the heat pad... I've just been leaving it on and the temps are holding on the hot side and the middle. I have two domes and have been using a 100W daylight bulb and then I switch the domes and am using a 75W infra red bulb at night but the heat doesn't seem to make it's way to the other side of the tank.