Algae ID

[matt 76]

Does anyone know what this algae is?

 

[csammis]

Are the leaves flat? If yes, I had a similar looking algae crop up shortly after I started my tank with sea lettuce in the sump. I never positively IDed it but I figured they were sea lettuce sprouts. GISing for "Ulva" gets some results like yours:

http://www.cibsub.cat/bioespecie_en-ulva_rigida-32835

 

[Moeshi]

Enteromorpha sp.

 

[Subsea]

http://marineplantbook.com/marinebookenteromorpha.htm