it's possible that they are fan worms and not a problem. if they are transparent, then you may have aiptasia - a type of anemone that is a real pest. a pic would help. if what you're looking at is a bunch of little white tubes with the fans on one end, they're your garden-variety fan worms and harmless. I'd leave them be in that case. If/when you add fish and crustaceans they may control the population for you. the only problem I've had with them is that they can settle in pump mechanisms and slow things down. regular cleaning of the pumps will handle that issue