Exactly right BHR. I encountered the heat/humidity loss issues with a 20 gal long with a sliding screen top. So I removed the screen, replaced it with plexiglass, drilled vent holes, turned the tank on it's side, and installed a Tstat regulated UTH. Now I've eliminated those problems and it looks pretty sharp. I basically took a glass cage and made it like we described a plexi cage. Here' a pic.