I have had bubble algae in my old 42g hex that I kept trying to scrape off that only got worse with each scraping
I tried an emerald crab that forgot about the bubble algae and began eating coralline algae and then my galaxea
It got so bad that I eventually tore down the tank, boiled each rock for 3-4 minutes, the cured the rock again and used it as baserock in a larger tank.
I admit, those were drastic measures. Since your emerald crabs are doing a good job so far, though not good enough, I would get a half dozen more to see what they can do for you.
Dang, sounds terrible
Good luck
