You may find some luck with h202. If it were my piece in my tank. Key words being MY TANK =D. I would turn off all water current and wait for things to be still. Then I would take 1, maybe 2ML of h202 and gently blow it directly onto the algae. Wait about 3-5 minutes then turn the pumps back on. Rinse and repeat every 2 days until the algae is gone.
I cannot recommend YOU doing it without first educating your self on the effects of h202 in the reef if you were not already aware.
I would hand pull or tweezer it off. Get a few emerald crabs to help keep it off. Check phosphate levels to be sure it doesn't come back. If you can keep to clean of algae it will heal that area with new growth.
Thanks for the suggestions Reefers! My PO4 is undetectable via Salifert. I've personal experience with H2O2 of the Oops kind-lol.
I was thinking of removing it from the tank and spot treating it with H2O2. Making sure all algae is removed before returning it to the DT.
I've also got some "Reef Primer Shot Coral Dip" I thought of trying. Supposed to help with STN.
Look at the first pic. Definitely algae growing. This second pic was after the h2o2 treatment.
I've got some PolypLab Reef-Primer Shot coral dip I'd like to try. http://www.polyplab.com/products/reef-primer-shot