After many years of using aspen, I have to say I am sick of the stuff and am in the process of changing to different substrate. We have had a hotter summer than usual in a house without air conditioning, which has made more of the snakes want to soak in their water dishes. Then the dishes overflow, and mold grows in all the wet areas. Yuck! I do like that Cyprus bedding will hold water and not mold. I will keep using that for my arboreal species in display cages, as well as my rainbow boas. And for all of my colubrids, ball pythons and boa constrictors that live in racks, I am currently trialing Carefresh bedding. So far, there hasn't been any mold, it is easy to spot clean, and I think that the snakes enjoy burrowing in it.