I am convinced that the best way to iradicate bryopsis and hair algae from your tank is to shut the lights off for two weeks (if you have corals this is a problem, I moved my corals into a holding tank with lights for a while), then after the algae is dead, you remove the rock and scrub it down with a toothbrush, Be sure your water has no nitrate and phosphate and you should be fine. It is just very difficult to get rid of once it has taken hold.