Is it spreading a lot? I have a couple, and i actually like them. I know it sounds funny, but mine dont spread and they add color to the tank. People always ask me why i have a marble in my tank lol. Yes, sometimes an emerald crab will clear it up for you. Whatever you do, just be sure not to pop one. Thats what spreads it. Good Luck!
PS, sometimes yellow tangs will clear it up, but i dont know what size tank you have