Sorry don't have time to read every post in this thread, but I had the same issue happen with off the chart phosphates and zero nitrates. I truly believe that either the Marco rock or Real Reef rock or both, held/stored up PO4 and then released it as the tank was maturing. I went crazy chasing the numbers down causing myself other issues. My first tank that I built using Live Rock (back when you could get it right from the ocean super-easily) never had this problem. I really dislike not starting with true "Live-Rock". I would bet a weeks pay that the rock is causing the PO4 boom.