Byropsis.... GGEERRRRR

[High tide]

Sure, you could totally kill your live rock and start fresh if you so wish, but if experience has taught me anything, another pest (or the same) will eventually end up on your rock. If you're not against adding another fish to your system, you could try a Scopas tang. I've found these fish to be extremely versatile algae eaters and have consistently eaten Bryopsis in the several different systems I have added them to. They have taken care of it every single time.