Depending on your CYA level, a 5 ppm drop is not unreasonable for a sunny day. That's why you measure just the chlorine lost at night when you're trying to see if you're still battling something in the water. Also, it is not unusual for the CC to only be 1 ppm--CC is removed by chlorine, but also by sunlight, which is also why we recommend you test at night and then early in the morning to see what's actually happening in your pool. Hang in there!!

Janet