I had a lot of humidity issues with my enclosure as well. What I found to work best was I got a 6" ceramic flower pot (Ceramic, it's heavier... a dog bowl or anything would probably work) and put some sphagnum moss in it, just a handful or so... then wet it down, and left maybe a 1/2" of water in the bottom of the bowl. The moss does a good job of absorbing the water, and then since there is a lot of surface area, it can evaporate quite well. My humidity was lingering around 40% and after I put that in the tank, it went up to the mid 50's. I did try to seal up the rest of the enclose pretty good, with the exception of a small vent in the back, but that may be worth a shot. You can get sphagnum moss at Lowes/Home Depot, and maybe other places. Most decent garden centers carry it.