Been dealing with cyano for about a year. Never had much issue in previous tanks, they went pretty well, decided to upgrade, this tank is just insane. Cyano will start to go away, hair algae appears. Hair algae starts to go away, cyano appears. Tank was started with uncured Marco rock but it's about 20 months old now. Nitrates are 1-1.5, phosphate .01-.04 depending on how much I feed. I do 10% water changes every 7-10 days. I do not run a refugium/algae scrubber/chaeto reactor, I do run GFO, carbon and carbon dose a small amount of nopox, 1.2 ml per day. Good skimmer. I have an eight bulb Sunpower sitting 11" off the water. I have tried what feels like everything. I have manually removed so much that I only have about half the sand I started with. I have tried reducing my carbon dose and it gets worse. I can up the dose and strip the water and it starts to die but then of course corals really suffer. I have replaced my RODI unit, I have changed my salt, I have tried more water changes, I have tried less. I have reduced my photoperiod, I have changed my bulbs, including changing the spectrum. I have tried 150% doses of chemiclean back to back, it came back within days. I have increased my flow, I have four MP10's in a 66g tank. I've tried feeding more, and feeding less, as well as switching to mostly frozen from about 60-70% pellets and flake. Two weeks ago there was lots of red turf algae, cyano really reduced at this point. I changed out the GFO, the algae started to die and cyano started growing on it. This has happened many times. Now the algae is almost all gone but cyano is rampant. I also had two of my torts die for seemingly no reason while most other corals and acros are doing fine to good. Except zoas, my zoas suck for some reason. This is colossally frustrating. We all know the time and money invested into our tanks. The only thing I can think of doing is completely removing all GFO and carbon dosing and let it go wild until it all balances out, but I am concerned about losing most of my coral. Or, since changing the GFO seemed to start this latest breakout (or maybe it was just the algae dying), just stop GFO. Maybe I just have way too strong of a light for the amount of coral I have, but I've never really heard of that before. I flat out am completely stumped. Any thoughts?