If I were to ever start using substrate I think Reptile Prime bedding would be my first choice. I've read and watched a lot of reviews and I guess it holds humidity very well and hardly ever has to be changed. I would love to use it for those reasons, but the risk of animals swallowing it and developing digestive problems just isn't worth it to me. It seems like it would be even easier for them to swallow this stuff than just about anything else, because it's so fine that it is bound to get stuck all over the rodents and the animals will no doubt be dragging it in their water dishes constantly. For those reasons, I have to stick with paper towels...