two other questions I have....I have seen in may pictures on here, people have put larger beautiful rocks in their terrariums. They do not look like the kinds of rocks one can buy at a pet store. How do you properly clean rocks you find outdoors? Are there any kinds of rocks that are unsafe to use because they give off minerals, etc.

-Is there such a thing as a self contained waterfall device that filters water through a pump, into a container and back up again without having to turn the entire terrarium bottom into the water fall? I guess I'm thinking something like those mini desktop waterfalls you can buy at Wal-mart except designed for use in a terrarium.