Algea ID

[Olivier]

I need help ID this green algea on my rock.  The tank has been up for november, 2009.  I added rock in december, 2010. I used to have a brown algea when I added rocks.one day it was gone. 2 weeks ago, this green algea start to show up.

Olivier

 

[The_Codfather]

Is it hard to scrape off? If so it might be coralline algae.. I have a lot of green oralline on my rocks

 

[Olivier]

green coraline ? i saw purple coraline but not green. I can not scrub it off.

 

[The_Codfather]

coraline algae comes in many colors.. but from the pic that was my first thought and now you say you can't scape off makes me think even more so.. what lights are you running depends on colors too I have 194watt PC's 96w 12k daylight and 96watt blue and I have red, purple, pink and two shades of green growing..
Pic of green and purple coraline algae

 

[The_Codfather]

coraline algae comes in many colors.. but from the pic that was my first thought and now you say you can't scape off makes me think even more so.. what lights are you running depends on colors too I have 194watt PC's 96w 12k daylight and 96watt blue and I have red, purple, pink and two shades of green growing.. and the greens are really taking off
Pic of green and purple coraline algae

 

[The_Codfather]

before I forget.. CAL and ALK plays a big role too in coralline growth

 

[The_Codfather]

Some more info on coralline algae colors and growth
http://www.saltwater-aquarium-online-guide.com/coralline-algae.html