Coral Colours and Amino Acids

[Marlin65]

Originally Posted by Ron99

I do suspect my Alk may have been a bit unstable so I am keeping an eye on that right now. That may also have been the source of or contributed to the problem.

I think this might be part of your problem. I just had a problem with the alk in one of my tanks and all my corals turned brown. They are coming back but it is taking some time.
I do think your fish load could be a problem. When I was running my other tank with fish I had great color then when I transfered just my fish over to my other tank my corals slowly faded in color they did not turn brown but the color faded out over a few weeks. I was not feeding at all at that time as there were no fish.