I use 2 under mine, works pretty well. Keeps the warm side at 93-94 and the cool side 82-84. I am planning on cutting a small hole in the lid of her container(with hardware cloth over it) so I can get a light to warm up the air some. My boyfriend's house gets a little cold at night, just because it's old, and I think she needs a little additional heat for the winter.

He's also getting me a thermostat for XMas, not anything fancy, but the middle one from Big Apple. Or if Matt can sell us something else around that price, that works better, then I'm game for that too.