If you just leave the "algae" in the tank it will just reform. It needs to be removed, not scraped or blasted back into water. Siphon it off your rocks when you do a partial water change. Wipe it off your glass with a scrubbing pad, and remove the pad after each swipe and rinse it in fresh water, real well, then repeat untill your glass is clean.. THe key is to remove the algae or it just becomes nutrients for new algae growth.
