I regularly dip live rock with corals in a 10% solution of H202 for ten minutes.
A good guide to identify most of the nuisance algae that plagues the hobby. Complete with pictures and suggested treatments
www.reefcleaners.org
Bryopsis pennata and B. plumosa
Some of the hardest to remove common species of macroalgae encountered in the hobby are
B. pennata and
B. plumosa. These two species have noticeable discernible midribs (center portion of the algae), that are wider than their branches. They also form a mat like root system on the rocks.
B. pennata (pictured on the left) has irregular and more sparse branching than its closely related cousin
B. plumosa which has more symmetrical and fuller branching. (picture coming)There are many, many species of Green Hair Algae that have feathery branching, and are not necessarily members of the Bryopsis genus, nevermind
B. pennata and
B. plumosa. Simply because the hair algae in your system has branches does not mean it is one of these algae species.
The reason hobbyists despise finding this algae in their tank is because cleaner crews rarely finish it off when they snack on it. Sea hares, Pitho Crabs, nudibranchs, urchins, Emerald Crabs, chitons, and even the larger
Astraea tuber will eat both of these species, but often do not consume it faster than it can grow, or the algae lingers half eaten.
PS. Check out reefcleaners link to better identify undesirable algae.