Until somebody specializing in dendronephthya comes, let me add my 2 cents worth:
Maybe some food with high pigment content, like NatuRose, Cyclop eeze (soaked powder, the whole crustacean is too big).
I have two kinds of dendronephthya: small with white trunk and purple branches, and large bushy mono-color with particularly large sclerites, several months only. None on them faded, the bushy one became more clean pink, with no carrot-colored highlights, and paler color was only on the new growth of the small white trunk dendronephthya.
Which one of yours has a problem with color, or you are planning to make them more colorful?
