I bought a bucket of chlorine and what I got is labeled Sodium dichloro-s-triazinetrione dihydrate granules. When I use http://www.thepoolcalculator.com, there are several drop downs. The one I'm using that looks the closest is Dichlor. There is not a percentage on the drop down, although the bucket says 56% available chlorine. Am I using the correct drop down?