I have had a pervasive bubble algae issue (despite low nitrates and phosphates). I seem to have created the ideal conditions for bubble algae growth and have been manually removing it from every rock in the tank for months. I also purchased pitho crabs from reef cleaners. These guys are awesome so far. They move around slowly, have tiny little claws, and don’t seem to bother anyone. I watch them just go after the bubble algae constantly. And they’re a bit entertaining—they sometimes bury themselves in the substrate and wear algae on their carapace. My experience with pitho crabs for bubble algae has been pretty fantastic. I hope they also work for you. I have had emerald crabs, but they don’t seem nearly as consistently interested in bubble algae as the pitho crabs are