I have a friend who wants to make the switch to Marine tanks. He has a couple of buckets of black flourite sand leftover from his FW tank. He says it will be fine for his FOWLR setup, that it's sand and once it's been with LR long enough it'll be "live". I don't know enough about this topic to dispute it, but I told him I don't think it's going to work. Is he right? Will this work?