i use ro water with no detectable, the saltwater i use has no detectable phosphates, the kent medium is changed once a week as is directed, i have a cprbakpak skimmer, the tank has been setup for 3 years at different compacities. its not an sps tank, but i do like corraline algea and phosphates inhibits corraling groth while promiting hair and brownslime algea. i think the proublem was the kritter keeper, as the phosphates has lowered to .5 after only 4 hours. i think the proublem was that the netbreeder became a factory for phosphates as food and waste became traped in the net it self.