Personally, I like it to where the top is a bit dry, but the lower parts of the substrate are nice and damp. I would not suggest keeping the tank too damp as it makes the whole a bacteria breeding ground. As well, Ceratophrys, as well as many frogs, urinate and defecate in their water. So if a tank is too damp, the frogs are going to urinate and defecate all over. If the tank is a bit drier, they usually do both in their bowl while soaking, which makes for easier clean up. Not to say you still shouldn't clean out the bedding often.
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Andy Maddox
AIM: thekingofproduct
MSN: Poloboy32486@hotmail.com
Yahoo:surfandskimtx04
Houston Herp Key
The Reptizone