In that case I might cover some more of the lid, maybe three quarters. But like Frogger said some variation is Ok. All I know is I never mist mine, but I dump their water bowl right into the substrate when I clean it, and the plants slowly evaporate it out. When they were in quarantine I just kept a sixteenth inch of water on the entire bottom of the tank. I guess my point is put more water into the tank in liquid form, and your humidity will take care of itself. Do not cover the entire tank top, they need air circulation or nasty stuff can grow. For the record I also think it is Ok top have a short dry spell as long as it rains afterward. Perhaps someone with more experience will comment, I'm kind of new to frogs...