Very cool project, I love Caribbean corals and wish they were displayed at more public aquariums. To me, the elkhorn looks light starved though it could just be getting established. I typically give them 700 umol/m2/s of MH. I see no issue with MH vs LED, I would just slowly increase and watch their reaction to avoid issues. People used to say that you had to use 65k lamps for them... I use 14 and 20k. ACerv is not found in the pacific. It generally is found deeper than APalm which I have only seen in 10 feet or shallower (Acerv is frequently in about 30 feet of water). I give Acerv about 300 umol/m2/s but they can handle brighter (500ish) for shorter periods of the day. The Acerv. Should start having stronger growth tips, better polyp extension. If not I would increase feeds and increase light for a few hours each day. Some of the other corals in there might react poorly to the increased lighting so placement is critical and can be challenging with corals from such different niches. Good luck! It is always fun to take your experience working with pacific species and apply it to protected Caribbean species that not many people have the privilege to work on.
