We've found heat mats at local pet stores and online, and they say to have built in regulator or whatever for the amount of heat, and if not I would build a rheostat. The thing I am wondering is, I use the bark for substrate and the mats at the stores said recommended for desert type terrariums with sand or gravel for heat conducting. Would bark still be fine? If so.. do I need to set the temp right on the bottom of the tank or on the actual substrate under the hide? let me know some tips. thanks everyone!