They are a problem, all I do is keep them from touching the SPS. I use needle nose pliers to pull them off rocks. I have used a scrub brush, acid, fresh water and a knife to try to remove them from rocks while out of the water. They tend to not like High flow or bright areas. I am just to the point where I try to control them. Eradicating them at this point seems impossible. Good luck, hope you can find a way to keep them in check.