The best option and cheapest is the moss, you can buy it at petco or petsmart. You keep it in their hide and keeps the humity in the hide high, since that is where they are most of the time, and it doesnt cause any mold or anything, but u need to spray it everyday tp keep it damp, and when u first put it in the hide. Also I recommend taping down either tin foil or cling wrap so its covering 70-90% of the top screen, as opposed to the wet towelwhich can start smelly musky. And moving the water bowl partially over the hotspot as well.