Ok either my water quality is horrible or I am doing something wrong here. I just got my Hanna checkers in the mail today and the phosphorus keeps giving me a 200ppb (0.613 ppm) reading. I'm thinking it's an error since that is the max reading it can give and my fish and corals are doing great. I'm not touching the vials (so they are clean), I add tank water, press the button, then add the reagent and hold the button. 3 mins later I get a 200ppb reading every time. Help!