I would pull it off and treat it outside of the tank. Read what reef cleaners says about either green wire algae or green turf algae. I suggest emerald crabs for intank cleaner.
A good guide to identify most of the nuisance algae that plagues the hobby. Complete with pictures and suggested treatments
www.reefcleaners.org
What is known as "
Green Turf Algae" in the hobby is really a generic name given to hundreds of different species of macroalgae that describe certain similar characteristics. They are coarse, wiry, and generally have thicker wider blades than Green Hair Algae. They may or may not have a mat like root structure, sometimes they just seem to sprout from the rock.
Turf algae that sprouts directly from the rock can be a pain to control, as it is difficult if not impossible to pluck it all. Once discovered it should be treated outside of the aquarium, perhaps by dipping the affected rock or frag in water treated with an algaecide.Turf algae that grows with a "root" mat can be peeled by pushing down on the algae as you scrape your thumb against the rock dislodging it in one swoop. Let it get big enough so you have leverage. The 3reef member who removed this piece did it perfectly.
Clean up Crew members that will eat Green Turf Algae include inverts with considerable cutting power like urchins, chitons, and emerald crabs.
Cladophoropsis, Green Wiry Algae
Species in this genus, and related ones, cling to the rock, and spread from a runner. The branches do not get tall, and they are often found with hobbyist frags or on live rock.
Manual Removal: Difficult. Macros that have fragile runners and creep along the rock are the hardest to manually remove. Do the best you can. Get a dental pick and get it all the first time and be done with it.
Clean Up Crew: Rock Boring Urchins, Emerald Crabs, Turbos, and Sea Hares occasionally pick on it, but don't seem particularly interested in it.6
