The Seachem DuoPad is a non-scratch, dual surface algae pad for glass & acrylic. The melamine foam side uses micro abrasive technology to easily remove algae from the sides of your aquarium, while the durable scrubbing side allows you to attack tougher algae deposits on the glass as well as uneven surfaces such as rocks. Melamine Foam, Micro Abrasive Technology with Added Durable Scrubbing SurfaceSafe for Glass and AcrylicNo Soaps or DetergentsEffectively Removes Algae From ScratchesBecause of the soft foam structure and special shape, they are ideal for getting into corners, little crevices, and even into shallow scratches that standard blades might not reach. They are chemically inert and unlike common foam cleaner pads from a department store, you don't have to worry about soaps or detergents. The white color contrasts against dark algae making it easier to see when areas are fully clean.