OK --- that sounds reasonable --- Perhaps I should start another thread for this question.

I have never seen a difference when I test for total chlorine. Using a DPD test kit --- Fresh reagents and careful attention to procedure. Free chlorine now is between 2 & 3 when I add the 5 drops of R0003 nothing changes. We shock regularly (once per month) and I really don't want to see any combined chlorine but I would think I should see something. Perhaps I shock too often??