As I push P4 down to the little numbers, 0.05ppm, i am seeing a direct effect on the reef. The anthillia that was trying to take over, is now dying back while the hard corals are prospering. The bubble algae in the soft coral tank is all dying back. It is obvious to me that corals like Xenia and waving hand are dependent on nutrients in the water as well as lighting. The mushrooms aren't happy either, they obviously like higher nutrient water. Not all my soft corals are reacting this way, just this type. My clowns aren't happy about the receding waving hand as that's what they host. The last of the Cyano from the bio bead debacle is about gone. But I needed more room in the main reef for all the gorgeous hard coral I have grown in the frag tanks. Remodeling is in my future.