In all my years reef keeping, i have never managed to burn any of the tips on my acros and have never really seen it before

so can any one confirm if that is what is happening to this birdsnest at the moment
I have recently changed my lighting & ballasts so i am assuming that this may be the cause, although i know that over dosing Potassium and Alk spikes can also cause this problem.... Potassium is at 380ppm & Alk @ 7..
Are there any other issues that can cause this? I am running ZEO and what is the best way to help this recover. Would it be best to cut off the affected tips? I have raised the lights for the time being.
Regards,
Simon...
