Hi Hernan, yes there are a few reasons why:
I had those corals under another light spectrum and intensity, when I move them they started to received less ligth and the color changed. The duration of light cycle changed too which causes that corals receive less artificial light during the day.
Also my fish feeding routine is kind of heavy, I feed my fishes twice per day every day of the week, that generates a high nutrients load that can cause darkening of tissue in Sps corals. Nitrates are under control but I want to have a better phosphate control, the qty of GFO resin that I use is not the optimal, I'm planning to change it but that's something that I will do in my next monthly maintenance.
I'm not concerned about colors at this moment, I want to give them a chance to grow and adapt to the aquarium again, this build has only 6 months running so is ok for me right now. My last build was Sps dominated but when I switch my idea to keep soft corals again my priorities changed as well as maintenance routines, additives and corals colors. My main goal is to create an aquascape with natural and nice looking, and to keep my fishes happy, in second place I will focus my attention to grow colonies from frags and provide better colors, but that's a process that takes time so is matter of patience.
Of course any recommendation and suggestions are more than welcome, that's why I created this thread, to share information and pictures of my aquarium and to get feedback and good advices from other reefers.
Cheers
Jeff