this has been an interesting topic for me. Not only have some of my zoos turned brown but other corals as well. All my water parameters are fine- Calc, Alk, Mg, Phos, pH. I am still planing on sending a sample to aquarium water testing service to check on some of the other element levels. However, my lighting are AI led system. I love the lighting. I have wondered if there is some spectrum of lighting missing in a LED system. Overall PAR values ARE comparable to most MH/t5s.
I had, however, never thought that I ran my lighting too long. Sunrise at 8:30 am for 1 hour sunset at 8:30pm for one hour. My LFS suggested I cut back on lighting. I think I will cut back lighting to come on at noon.