always say more flow to the problem ones,,it weird how one colony does good and the one right next to it has issues..IDK..
over the years Ive noticed that if i keep my salinity around 1.023-1.024 they seem happier/plumper and keep Mag around 1400. ALK high 8s. That what seems to work for my system..
I dose Iodide in my ato,,very low dose but it keeps in the water constantly..
Ive tried leds then T5s and just this past fall halides,,honestly the halides were a blessing and if a polyp dont like halides ,I put them in the tank with T5s,,usually find a sweet spot between the two lights for the majority of them but there is always one colony that is never happy..
All my tanks are on one sump..so just the lighting difference sometimes makes a difference..
increase flow and run some GAC in a reactor,,see what happens,,pretty harmless approach but start slowly here..
OH,Yeah,,NEVER pick a "Favorite" coral or fish in your tank,,,,if you do,,it is a sure death sentence to them ..LOL