It should either be aged for a period of two weeks with strong aeration or sterilized in another fashion before using it in your tank. There are all kinds of nasty buggers in NSW
that your tank will probably not be able to cope with. Also, this will give any planktonic organisms time to die off so they don't pollute the tank.
Living here in Panama City Florida, I dream about setting up a system that would allow me to simply draw NSW
right out of the Gulf and use in in my system. But for now, salt mixes are much easier to use.