I was thinking about using a peice of styrofoam coated with dyed thinset mortar for the bottom of my terarium. Has anyone done this? Any opinions? I've seen "rocks" made with it, and I want a more natural looking subtrate, so I was wondering about that as a "subtrate". I'm wondering how it would stand up, and how it would be with waste, and water, etc. and how it would be with the UTH. I like the polystyrene, but I think it's too much for a 20 gallon. Any advice? 


