i have it on 2 rocks and i have alot on it on the third rock i have a rbta and i aint tryin to take him off, its true what ur sayin that when u pull it off they just grow right back. when im goin to do is get some new phosban media and some carbon and change my rodi filter pads and get a tang . but i really dont want to take the rocks out ! but i might have to and scrub them down!