Gosh. In tank scrubber. I had a couple rocks that bloomed like that. I plucked as much as possible by hand and with good forceps and added 2 urchins. It took a couple weeks but it's under control. Mostly gone. The urchins don't eat it till you pluck it first.Yes.
Which particular kind of urchin do you have? My Tuxedo eats only encrusting pink algae on the rocks and the back glass. I can't put long-spiked urchins like Diadema setosum in my 40G.
I used pincushion in that tank. The prefer rocks to glass. They also eat coraline but eat most things in their path. I think they keep this stuff under control because they keep it scraped to the root while eating other algae. I have 2 in a 55, 2 in a 75 and one in a 30. I let lots of algae grow so don't have to feed them. Good luck.
