That stuff grows like a weed. In fact, isn't it considered a noxious weed in Florida? It's also pretty big, isn't it, for a 5 gallon? I would buy 1 single plant in June for a half-barrel. By mid-July, it had spread over the whole surface and I was weeding it out constantly. I tried over-wintering it once in an old tank, and it did not last, I think it needs very high light.