I'm dealing with a little bit of a PO4 issue right now so I just stepped up my water changes to 20% TWICE a week! You may note that this is a 500g reeftank so for those of you with stock in Reef Crystals, I congratulate you. I am otherwise running GFO and GAC, topping off with Kalk, lots of flow...all the usual ol' school Berlin stuff. Decent bioload right now; good fish population, TONS of SPS frags... I just cut down a bit on the feeding though, hoping this will hasten the lowering of the phosphates. I have noticed that many of the frags have begun to color up a bit more lately. I don't know whether this is attributable to the regimen, the phosphates themselves ('I've heard this from several sources'), or to the fact that just they're 'settling in' though.