Update: On Sunday, 7/14, I removed all my live rock, scrubbed each piece with a stiff toothbrush, rinsed in a bucket of water from the tank, put 12% food grade hydrogen peroxide on each spot where the GHA had been, rinsed again in the same bucket, and then rinsed again in a clean bucket of tank water. I also removed the large marine pure block from the sump and did a 20% water change. The live sand is only 6 months old so I didn’t do anything to it.
My parameters after all this were:
NO3: 0.1
PO3: 0.06 (Hannah ULR)
Alk: 8.4
Calc: 420
Sg: 1.024
I am continuing to dose 2 Part ESV 7.5ml per day and 10ml NOPOX per day.
Here are some current pictures of the tank after the treatment:
I plan to switch back to Red Sea Coral Pro salt. I had been using the blue bucket. I hope I can keep it at bay now.