I would rather treat them while they are in the tank rather than removing rock/whatever they are on. To me it is just simpler to turn off my circ pump, add the drop of aiptasia control, wait 2 mintues, then turn my pump back on. Really-- I don't always turn off my pump. But hey, if it works, yes it. I have had the same bottle of aiptasia control for over a year now, and i think it was $10 or less.