Qt fish, dip corals, condition rock and sand, and for inverts, I give them a bath in new saltwater just to be sure their water isn't bringing something. But the way things are done by larger companies, your coral will not tend to have fish parasites, but coral predators, because it is not kept with fish. Ditto separation of other items. The bigger and older your tank, the more paranoid you should be, and no life is just to toss off, but your risk is fairly small if you just follow the habit of dip for corals. qt for fish., rinse for inverts. FYI, snails will eat fishfood, and should be supplemented in a new tank. Also, they will not eat every type of algae. Mostly they will help dispose of any fish that die, which is what is actually meant by clean-up crew, and why diversity in CUC is a good idea.