While we wait for the doctors, I'll try to give you my humble opinion.
Normally when that happens is related to light an/or nutrients and/or "poisoning" (metals, toxins, etc.) .
I don't know about your lights... would be good to make sure the LEDs you've got are ok for the polyps. I use T5s and other people would be better to help on that... the LED doctors...
You've got lots of things there...
I would remove the GFO and GAC first.
Temperature of 79F is good IME.
Alk from 8 to 10 would be better.
Try to use good water RO/DI/AC for replacement and water changes.
Stop vinegar and vodka. You don't need that.
Try to feed quality dry coral food to the polyps at night.
You can try Coral Frenzy, for example.
Turn off pumps and skimmer to target feed them once a week.
I would try those first and see what happens.
Please don't think because you'll try one of the above it will make them look better from day to night. It will take a while...
make sure you have nothing on the zoas, like shrimps or crabs, damaging them.
Predators?
BUT, wait for the doctors before you do anything ... :thumbsup:
Grandis.