This is why I think it's important to use a very thin layer of substrate if you use belly heat. Aspen can work fine...but put down just enough to absorb waste (which is all the substrate is for anyhow). They don't need a thick cushion of bedding. I aim for not more than 2-3 degree difference between the floor of the enclosure and the top of the substrate....whatever it may be.Originally Posted by 581775017