I'm with Deborah. I stopped worrying and started observing what kept my BP happy. I have it dialed in now and he chooses exactly where he feels like curling up. I have temps ranging from 90 all the way to mid 70s on the walls and he cruises around the enclosure and decides where he wants to rest. Then again I do have a 4 foot by 2 foot PVC and it has made a world of difference in stabilizing the temps. That to me is the key, providing stable temperatures.