not dumb questions at all!
I have never heard the garlic thing, but that would be neat if it were true,
I don't think sea salt should be used in a FW
aquarium, i think you would be better off just getting some aquarium salt. I think the sea salt you buy at the stores may have additives, and is not fully natural. Aquarium salt isnt that expensive anyway, here, sea salt is more expensive than FW