I have heard about people using water softener salt but I was always worried about additives in it and then I saw this (link below) is 99.8% pure and the other one says it contains neither YPS nor iodine and is NSF certified. Are these OK to use? Is one better than the other?
North American Sure Soft Pool Salt 40lb Bag
Sure Soft Premium Water Softener Salt Pellets 40 lb. bag
North American Sure Soft Pool Salt 40lb Bag
Sure Soft Premium Water Softener Salt Pellets 40 lb. bag