Yes, bromine can be used in salt water just as chlorine can. Just note that at least some of the salt needs to be bromide instead of chloride in order to generate more bromine when you add an oxidizer to the spa (chlorine or MPS). If you want an electrolytic generator to make bromine, then most of the salt should be bromide (it still works if it isn't, but you end up making chlorine first that then converts bromide to bromine). And yes, you can use bromine tabs in a spa with salt though I'm not sure why you want a high salt level unless you are using an electrolytic generator in which case you wouldn't need the bromine tabs.