Again, I'm not too sure I'm reading these things correctly but it seemed that it read the highest levels. For the Chlorine side, as soon as I put in the yellow drops and invert, it just turns yellow. Looking at the chart provided, maybe that's what it's supposed to do. I will do the tests today that you (Watermom) mentioned above. Yesterday I was home from work, today I'm not so it will take a little bit.