I consider myself an expert on bryopsis lol as I battled it for so long and finally won. Don't even bother with trying to get predators, they won't eat it. I tried em all, sea hares, urchins, crabs, nudis etc u name it I tried it. This stuff nearly took me out if the hobby. So it turned out that the solution was simple..... Kent tech m. After dealing with it for over a year I took my mg levels to 1600-1700 ppm and it was gone overnight. Now I wish the story ended there. I didnt leave my mg levels high enough for long enough because mg is tough on inverts. Snails literally stop moving. Needles to say in order to really get rid of mine I had to keep the levels there for 3 months. Lost all my inverts but lost the bryopsis as well. I noticed that it seems to be particularly hardy in areas that I used reef epoxy. It grows out of the cracks and on some of those areas I had to literally drill the section of rock out as mg didn't seem to get it. Good luck!