This is some of the hardest to remove 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 are fast growing, and form a mat like root system on the rocks. Algae that grows from mats, instead of singular holdfasts, are harder to remove if they spread in your tank. This is due to the tedious work that is required to remove all of the algae from the surface it is growing on. Any piece that remains will likely continue growing.
There are many, many species of Green Hair Algae that have feathery branching and look like bryopsis, and are not necessarily members of the Bryopsis genus.
Flux does Not always work as again, you must get to the root and remove it for total removal. Remove all you can by hand. Just be careful about it, and if you can pull the rock out to remove it all the better. If it has taken hold in the sand, sift it out with a net. If you don't remove the rhizomes (roots) it will grow back. Also. starve it out - if you can lower nutrients nuisance algae has a harder time taking hold, or coming back after manual removal. Repeat every time you see a little bit come back. Try to be aggressive when removing these species.
Some cleaner crew that will help with this are : Pitho Crabs, urchins, Emerald Crabs, chitons, and even larger Astraea snails.
