If its on the rock, yes take it out and try to scrub it off with a toothbrush or such in a bucket with saltwater. I never tried this method, but read about it. Worth a shot, I'm going to try this on a few pieces of my rock tomorrow. A lawnmower blenny worked well for my first run in with this. Since I have lost him, for no good reason, the algea is back. Also, like stated above, those factors can cause the problem, and I am still fighting those.