Had a freak out yesterday when I checked the temperature of my boa's warm side and saw that the under tank heater was still not warming up the cage. Eventually I settled on a ceramic heater since my boa seems to like being on his tree more than his hide. I've yet to see him actually go into it and sleep, though I have seen him slither through it to get to his tree. The girl at the pet shop told me that keeping the under tank heater on and adding the ceramic heater would be fine. I'm afraid it will be too much heat. I also bought a digital thermometer with probe to keep on the warm side where I placed the ceramic heater and so far the temps are good. So, should I keep both or remove the under tank heater?