My pool is probably 4 ft deep on average and I would say that I put at most 5 inches of water in during that time frame. This is my third year of chlorine(I used baquacil for 3 yrs prior to that). My second set of readings is about what my normal pool readings are all summer. I double checked my test results that I came up with aqua chem with pool strips and the pool strips also showed zero chlorine and looked in line for ph and alkalinity with my aqua chem results. I will test tomorrow morning again as well. Oh, and I did test the before I put in any chlorine and put the muratic acid in prior to that as well. I only tested chlorine results again after I put in the chlorine.