Are you using a large water bowl? I too am using glass tanks(40 gallon breeders) for my baby sunglow and my pied girl and using aspen as well. I keep a steady 50% humidity and that's with just a large Zoo Med water bowl. If you cant get it up like that, just buy a Tupperware or any of the plastic bowls with tops at your grocery store. Then cut a "U" shaped hole in the side and put some moist moss in there and you wont have to worry about humidity. I wouldn't mist the aspen too much as aspen tends to like to mold if left wet, about the only downside I find to it personally.