[scotkenny]

The harm in leaving them alone would be the reproduction rate.They multiply like crazy!They thrive in a nutrient rich tank.I would def employ the flatworm exit and be prepared to dose more than the rec amount and multiple times.A wrasse would help but any reef safe variety wouldn't take care of a full on infestation by themselves.I would take some sort of action and soon.I had these in my 120 for quite a long time.I would regularly use a canister filter w/micron filter that I attached a turkey baster to to blast them off and suck them up.I could take out thousands and within a week it would look like I never removed any.They will get on your corals and practically cover some types.Nasty lil buggers.Nuke em i say ,then get a wrasse.