Ive been battling these in my main tank very hard to get rid off. My copperband wont touch it and haven't found anything besides joe's juice or kalk. Ive heard some puffers or large angels might take care of these but In my 180 their are to many places I phyically can't see or reach so the joes method only works as good as I can spot them. They spread like wildfire. I would remove the rock and treat it if its a large tank.