I am having the same problem. My chlorine tests low but according to the parameters that came with the salt water system, it is supposed to be low. The only way I can keep the water blue is by adding chlorine, and a lot of it. They told me at the store that if the salt water system was not working, the red light would come on and it's not on. Also, I tested the salt and that was a bit on the low side. Should I add salt? The store tells me I never have to add salt. Also, it turns green literally before my eyes. In an hour it will go from blue to green. I added a gallon of liquid chlorine yesterday and within an hour it was back to blue. Of course now the chlorine tests high because I just added a bunch. All my other numbers tested within the limits. So my questions are how do I know if the system is to blame, and should I add salt?