Quote Originally Posted by Oclat
"Any idea how to find out?"
Just test your water and use the bleach calc. to see if it is the strength that it says it is.
I dunno ... I used the calculator last night to determine the ppm increase when adding a 1.42 gallon jug of Chlorox. It told me that amount would raise it by 5.5 ppm in my particular pool. I tested with Ben's kit about two hours after adding a jug and my FC had increased from 6 to 15 (I am running a high CYA pool).

I'm not sure how precisely the calculator aligns with reality. Or maybe I goofed it up somehow. I'm awfully new at this.

-Jim