Seachem Algae Pads 3 Pack
The Seachem Algae Pads are non-scratch algae pads for glass & acrylic. The melamine foam uses micro abrasive technology to easily remove algae from the sides of your aquarium. They are particularly effective at removing algae from scratches. They are chemically inert and do not use soaps or detergents. Their white color contrasts against dark algae making it easier to see when areas are fully clean.
More on Melamine
Melamine foam is incredibly effective abrasive cleaner. It has a microstructure as hard as glass, but because of its open-cell structure it remains flexible. It performs on stains a lot like extremely fine sandpaper. In the aquarium, it easily removes algae by scraping with its extremely hard microscopic filaments.