Salt is a natural water softener and is helpful in drawing impurities out of the skin.   The salts have a low Ph balance so they are safe for use in your jacuzzi.  Salts dilate your pores, preparing the skin to absorb the trace minerals that the salts contain.  In homeopathic medicine, like cures (heals) like.  As our bodies are made mostly of water (salt water), salt is then the best and most healing element in which to bathe!