Would it be stupid to try to have part sand and part gravel? Like remove the gravel from 1/4 of the tank, and fill in with lots of sand, of course they would end up mixing some in the middle. I'd have to learn more about the pros and cons of gravel and sand I guess. I actually like the look of gravel quite a lot, at least for now. And it says that sand is harder to keep clean, etc -- probably snails can do a lot of it.