I tried both sea hares and lawnmower blenny. Sea hares do not last long. Both died within a month or so. As for the lawnmower blenny, I did not have a chance to see if it works as my open brain took it for dinner. I came back one evening and found the tail part of the blenny sticking out from the open-brain's mouth
I found Chem-Marin for Hair algae (got it from Big Als) worked well.