I've personally had success with doing a blackout. I have no clue what type of dinos or honestly any real details. I was still very new to the hobby then and basically followed some directions I received from a seasoned reefer. I let them grow to the extent that the entire back of the glass was covered, I had no clue what they were. Another thing to mention is with the majority of them on the glass (which looked like a brown stringy bubbly shag carpet), manual removal was quite easy and is likely the reason the blackout worked so well.
I did a total blackout for 48 hours, used only actinic lighting for 12 hours, saw some pop back up and did another blackout for 24 more hours. Followed by 12 more hours of actinic light only, then full light and they never returned. I have no doubt this probably wouldn't work in every case, just reporting my own experience.
Also, at the time I don't recall having any SPS, a few LPS, and many softies, but didn't sustain any coral loss.