What is this?

[RaymondL]

Tank is 9 months old and noticing these thick hard strings of green filament on the rock - they aren't appearing in dense clumps, but are showing up as single strands here and there.

Including a picture here to assist with Identification.

Hope someone can help with this - thanks

 

[ReeferHD]

looks like chaetomorpha macro algae. often used in refugiums.

 

[RaymondL]

looks like chaetomorpha macro algae. often used in refugiums.

Now why didn't I think of that - considering I had that in a refugium before, so maybe some strains got out. Thanks for the note.

 

[reeftivo]

chaeto doesn't root so it's easy to remove if you wish. i wouldn't worry about it unless it's irritating corals or unsightly