Just wanted you to know, in my tank the water is the moisture source and I can make humidity by covering part of the top with plastic over part of the lid. I always leave part open so they get air. We are into colder weather now so I cover it this way if the temp is down at night (I know its the outdoor temp) but, even though the furnace runs, I notice a difference inside the house especially when I get up in the morning. My water has a small submersible heater at 76 degrees, so, I get humidity for them if they spend too much time in the water I know they might not be warm enough. Hope this helped.