I can control the humidity waaaay better in my tanks than in my racks. The secret is to cover the top with plexiglass. Measure the recessed top of the tank and cut a piece of 1/4" plexi to fit, then drill 3/8" holes in both ends. If you start with about thirty holes on the warm end and about twenty holes on the cool end this should be about right (you want more holes on the warm end than the cool end). It's nice to have an assortment of plexiglass tops on hand. Some with more holes and some with less. This way you can have whatever humidity level you want simply by switching tops. I can keep ANY tank at ANY humidity level. When a snake is going into shed I just pop on a top with fewer holes and get a perfect shed EVERY time with EVERY snake. It's a bit of work at first, but well worth the effort to never have to worry about humidity again. My snakes always have cool fresh water, and I never have to mist.