I learned that oxydators have to be used very carefully, particularly in combination with UV.
With my 25watt UV there was not a problem, but then I added a 39W UV and near crashed my tank, first in the evening all seemed to be good then when I woke up all corals were closed and no polyp extension and accro were all brown and lost their colors. UV seems really to increase effectiveness
I took off the oxydator fortunately they seem to recovery slowly after a few weeks.
Unfortunately I have a white spot outbreak in my tank after adding a new fish and this after quarantine them, give them a fresh water bath, rally bath and methylene blue bath before put them in the aquarium! i can't believe that near 15-20 years I never lost any fish from sickness, had no Uv, no oxydator, no quarantine, not bath and then suddenly a crash and now every time i add a fish a problem!
As I have this white spot outbreak I added again the W oxydator unfortunately 6% seems to do not a lot, 12% corals closes after a few minutes. So what can I do? 6 is to low 12% too much? I have tried today to add to the 6% W oxydator an Oxydator A at 12% , for now corals seems so so acros don't mind , Euphyllia are half open ( but not sure if it comes from that) just the anemone closed and become very small But I'm willing to lose the anemone if all the fish survive.
Or maybe someone have an idea how to fix this naturally?