Moisture levels: Are you sure?
I've never kept dart frogs but I've kept salamanders, tree frogs, etc., many different amphibians... Do dart frogs have significantly higher needs for humidity than most temperate amphibians? I've never had to do things like close screens off with any of those species or monitor the humidity levels... I just made sure the substrate\plants didn't dry out.
Has anyone ever had a frog desicate under conditions where the substrate was still moist and the plants were growing? Or is the high humidity just a way to get the frogs more out in the open for easier viewing? With all my other amphibians I actually gave them considerable air flow usually by a screen top but all of those were temperate species so maybe that makes a difference too. What are your experiences with this?