Are you sure your doing the CYA test right, many people read it backwards the first time doing the test, 0 would mean the sample stays clear with the view tube full of the shaken 50/50 mix of pool water with CYA reagent R-0013.
You need a test for salt level to know how much needs to be added, once you have that you can feed the numbers to pool calculator and it will tell you. You can buy pool salt at any of the big box hardware stores, or you can use water softener salt as long as it is pure sodium chloride, it just may not dissolve as fast.
You need a test for salt level to know how much needs to be added, once you have that you can feed the numbers to pool calculator and it will tell you. You can buy pool salt at any of the big box hardware stores, or you can use water softener salt as long as it is pure sodium chloride, it just may not dissolve as fast.