If you put a fan you may lose heat on the warm side to, and you will fight with humidity I would think. When you spray the tank don't spray him directly because he will more then likely not like that very much. When spraying you don't even need to spray the substrate everytime, just if it feels or is starting to look dry. I usually just spray the plants and the walls and the substrate every couple days. Towards the end of the month you may have to spray the ground a little more often but that's also a good sign its time for a substrate change. If you spray the ground everytime you mist you will end up with soaking wet substrate within no time at all. Remember you just want the substrate damp not dripping wet.