Most people use sodium in their water softeners. I use potassium chloride in my water softener, but it's six times more expensive than regular softener salt. And it seems to clog up the bottom of the brine tank more regularly, so there is more maintenance required to keep it functioning properly. Every 4-6 weeks I have to clear and break up a "salt dam" at the bottom of the tank. Here in Florida sodium chloride is six dollars for a 40 pound bag, while potassium is about 33 dollars per 40 pound bag.