Acropora Agonizing.

Have you ruled out red bugs? They can be very tough to see and do result in loss of PE and fading colors. Also, the timeframe seems about right. So, just because you haven't noticed them, doesn't mean they aren't there.

Another possibility is that your playing with your lights too much. I've found acros do this when I play with the settings on my AI Sol, or switch MH bulbs. They just don't seem to like changes in light. I guess that is the curse of adjustable LEDs LOL.

 

The tank is over a year old, so I hope age is not the concern. I'm willing to believe lighting issues. I am careful to keep lighting stable, but I've gone through a couple of changes recently that could definitely be to blame. I'll try maintain more stability.

I've not seriously watched for redbuds. I'll look and see if I can find any evidence. As for stability, my Hanna testers day I'm rock solid. I dose 2 part using auto dosers about twice an hour over a 16 hour period.

I have a new piece I'm going to put through a MUCH longer light acclimation and see what happens.