right, and the amount of bacteria in a sealed bag of sand sitting on a shelf in a pet store for who knows how long is debatable. i would use the dry sand (thoroughly rinsed before adding to the tank so to remove any dust).
i like to use buckets of salt labeled "reef grade" or "reef salt" because they are supposed to be closer to natural sea water. while no salt mix is consistent due to settling, i have found this to be true, for the most part.
would i use a reef grade salt for a fowlr
? nope. instant ocean would be my choice until i was considering adding corals.