John, I'm so sorry. It does happen to all of us. I think I saw your tank early this year and it looked great!
I've been quietly battling my own issues. I figured out my problem but it took a long time. I had transitioned from bare bottom to crush coral substrate and had not problems...for a while. I had also switch to ReeFi lights at the same time. At any rate, my brother eventually helped me figure it out (he does tank maintenance for Premium Aquatics). Go figure, my issue was a buildup up nitrate, which let me to start carbon dosing. Well I ended up with too much phosphate, hair algae growth and then GFO. Eventually I dealth with the issue and pulled most of the rock and substrate, and got it back into balance.
So hang in there. We aren't proud of our failures, but it's part of the hobby and we all benefit from talking about the hard parts of reef husbandry.
Forgot to add that I lost a lot of SPS, but luckily a few nice pieces survived and are clawing back--Like my Walt Disney which was just a spec on a rock at the worst of it. Now encrusted to about a quarter size with several branches starting.