Probably been overfeeding and testing with a lousy test kit. My new colorimeter shows it's embarrassingly high. (2.4 - ouch!)I have granular phosphate removal media in a forced flow canister (2 little fishies) but my question is how often will I need to change the media and how long should I expect to take to get it down to a near zero reading? Does it become saturated very quickly? I already do 50 gal water changes q 2 weeks on a 180 gal tank with RODI water and Tropic Marin Pro Reef salt. Any other suggestions?