I have a standard length 55g, with just the 2 flourescent tubes that came with the setup. My substrate is pool filter sand, and I have resin rocks and driftwood-looking ornaments, and silk plants. I would like java moss to cover the fake rocks and fake driftwood. Can I buy some, tie it onto the rocks, and then just leave it to grow? Doesn't it have to have sand or SOMETHING for the roots to grow in? Sorry for the stupid question, but it just sound too easy to be true.