Diatoms growing on coral?!!!!!!

[mattypw]

Hi guys, I'm have a lot of purple diatoms growing all over my tank, which is bad enough, but now it seems to be growing on my green star polyps. There not dead, but fewer of them seem to be coming out, and the purple coralline algae is covered by dark purple diatoms. Any tips on how to get rid of it? I'm afraid my corals are being choked off from the light

 

[Michael]

diatoms is usually brown, are you sure were not talking about cyano bacteria here matt? is it slimy and reduces a bit at night then is back with vengence in the day?

how old is the set up?
how big is it?
what biological filteration is there?
how many fish have you got?
how often do you feed?
what lighting have you got?
what flow have you got?