Hi Dudley - ok - you seem to be 100% spot on, with your ID of Bryopsis.This is what I did to win over the evil crap that is bryopsis:
- increased my magnesium to +-1400/1500 (using epsom salts)...
- decreased my feeding - to once every two days....
- decreased my lighting period to 5 hours a day (for my corals and anemone)
- upgraded my skimmer to a huge skimmer
- increased my water changes.....
- I also "cooked" my live rock (by putting seperate pieces of liverock in a tank containing salt water and a power-head - in the darkness, for a period of about 6 weeks)....
This all helped me over come this evil....
Good luck mate! I hope that some of these would help you too!