It's quite a problem in my tank. Hard to believe older MH
bulbs would be the sole culprit. Other light loving corals are doing well. I have 3 kinds of gorgonian, green tree, brown finger leather, green star polyps, green hary mushrooms orange ricordia mushrooms, brown bullseye mushrooms (all these shrooms
are not showing ill effects), unknown type of acropora, green frogspawn, pulsing xenia, various feather dusters, large population of vermatid snails, 3 colonies of button polyps, copious amounts of coraline, and of course a large, long tenticle anemone. Nothing looks sick except the pink and blue shrooms
. The pink ones are almost gone, only 2 or 3 small nubs left.