chaibill - flip back a page and re-read liv2padl and TKOS's replies. As TKOS says, there is already salt in your tap water, and liv2padl covers all the necessary uses for aquarium salt as well as discussing the misuse of salt in aquariums.
Unless I'm treating for ich, I wouldn't, and never have, used aquarium salt in any aquarium. I do use Instant Ocean for my brackish fish...but then again, they're brackish and need it to thrive.
Eric