with my set up (its for tree frogs at the moment but im setting up one basically identical for cresteds) - see photos in 'show us your vivariums thread in photos of other exotics my humidity always stays between 55 and 70 and i dont have to spray other than to water my plants. Because the bottom have water circulating around it, it evaporates keeping up the humidity. and i have a 45X45X60 tall exo terra so its not a small tank. I researched alot and perfected my design before building it but now its workings its spot on! Cresteds have the exact same ideal requirements as my Whites tree frogs (just have different tolerances) so im just replicating my exisitng tank with a few added cool features like a better watefall (my ones a bit lame and broken at the mo you cant even tell its a waterfall in the pics)