SPS tank, third bout of dinos started the last couple days after blowing off some cyanobacteria aggressively last week. P04 is 0.04 on Hanna, no detectable nitrate. Carbon and GFO don't seem to help...debating the H202 method again and actually dosed 1cc/10gallons to my 120g tank. Any other ideas? BTW, I did turn the lights off today and will leave them off for a couple of days, but I have some SPS frags coming tomorrow too....so, don't want to keep them in the dark too long after transit.