I really can't comment on the phosphates, but the question I have is about your chlorine reading. You say that you have sufficient chlorine at 1.7. Without knowing all of your test readings, it is hard for us to know if 1.7 is sufficient or not. Please post a full set of water testing results (FC, CC, TC, PH, alk, Cal hardness, CYA) and tell us what type and volume pool you have. Then, that will help us help you. Welcome to the forum.