How does salt water chlorine generation work?

Salt (NaCl) is made from sodium and chloride (chlorine).  When the water in the pool passes thru the “cell” electrolysis is used to break down the salt into usable chlorine which then treats your pool.  The average residential pool will use about 100-150lbs of salt per year.  This is mostly from splash-out and backwashing as evaporation does not affect the salt.  Total cost for 150lbs of salt is about $35-$40.