All I can say is I use the calculator and place 12% in the bleach spot as I use ch. No problem though, Yesterday my 2006 said add 3.5 cups of 12% and 1.2 cups muriatic acid. I did and today my pool is sparkling. I cannot use the bleach calculator but since I cannot trust cheap brands anyway I'll just stick with what I get from the pool store. BTW can a chlorine granular be used if it is put in water first? I have a fiberglass pool and don't want a floater.....Thanks again Dave