The cypress moss is a great idea. I had the same problem with mine, the humidity fluctuated wildly throughout the day. Heat lamp, cold house.....

Anyway, the cypress moss works great and once it starts to dry out, I just spray it in the morning (kinda like dew) and it's good all day long. The stuff is mad cheap and lasts forever. You can get it from pet stores-they sell it in bricks or from a nursery.

good luck