Thanks for the reply! Two sounds like a good number in a 10g tank. I actually have a spare 29g tank that I'm considering using, but I haven't decided yet. I guess I could keep a good number of frogs in there if I wanted to.

With the 29g tank, could I make it a planted terrarium with real plants and just keep a couple of frogs so that it would be (sort of) like a closed system where the plants and soil take care of the waste? Or would I still need to replace the substrate every couple of weeks to clean out the waste?