That looks more like hair algae than the bryopsis I had in my tank. Mine was about 4-5 inches long with a feathery fern like frond. It was actually quite beautiful except for the fact that it was completely over-running the tank. Here's a link to my bryopsis story on how I got rid of it. The short version: I used Continuum bacter clean-M.
http://hioceanfront.com/bryopsis-alg...and-treatment/