New growth on rocks?

[Johnson556]

After finally beating cyano all was well for about a month. Then these dark green patches started forming all over my rock work covering coralline as well.

It brushes off very easily and has a sandy feel to it. I’m not exactly sure what it is, but it keeps spreading.

I also just found an AEFW on a colony as well. I’m about one more event away from tearing the whole tank down, setting up a QT and starting over.

 

[ndrwater]

Looks like green Coraline algae. Coraline comes in many colors from yellow to the purple we all seem to like and many colors in between

 

[Johnson556]

I have green corraline algae, I can assure you. This is not the same stuff. This flings off like no problem, I can scrape it off with my finger/nail easily

 

[Johnson556]

I just noticed yesterday that when this stuff grows it removes/kills the coralline under it. My rocks are completely purple except for where this stuff is forming. Once i scrape it off the rock underneath is white .

 

[Johnson556]

 

[Johnson556]

I still have not figured out what this is