Hey Tom. I wondered the exact same thing when I was having some problems: "I wonder if the LR is saturated with phosphates and it takes a long time to pull it out." There is evidence that after time live rock can absorb phosphates and leach them back into the tank. I took out established live rock with no corals, other than mushrooms, growing on them and "cooked" them in batches, like maybe a third of the rock at a time. I should also add that I started this process after I had to tear down the rock structure in one half of my tank to catch a Powder Blue tang who turned into a turd and killed almost everything in my tank. So I disturbed the substrate and the base rocks and figured it was a good time to clean out the rock. Put them in a dark room in salt water with a heater and a good powerhead. Every time you do a water change in the aquarium, use the tank water to change the water in the cooking chamber. You should "cook" it for a good 45 days. You will not believe the amount of crap that comes out of your rock. You can add a bag of phos guard in a media bag to help speed up the process. PS. The tank looks killer!