Something weird is going on. Getting ready for the season, I just adjusted my calcium hardness (260) and added sodium bicarbonate to up the alkalinity. Rather strangely, it didn’t go up much (70). But, the strangest of all is suddenly I get ZERO chlorine indication! I know there is chlorine in the pool. I put a gallon of 10% bleach in 2 days ago and I have a float with three 3” tablets (to increase the stabilizer which is below 30 right now and also to add chlorine). I checked my chemicals with city water and a drop or two of bleach and there is nothing wrong with the test kit. Anybody got any ideas what could be causing this?