We recently got our pool and are first time owners. We've googled, read instructions, etc. but just can't get it right. The ph level is reading 7.2 and the ppm is 0. I've learned that the ideal ph level should be 7.5 and the ppm 1.5, but I could be wrong. We've added liquid chlorine but the reading doesn't change. What are we doing wrong and how can we make sure that we are maintaining and sanitizing our pool correctly?