Use these special cleaning cloths to effectively remove algae without scratching. Available in packs of three these special cleaning cloths have a smooth side for regular cleaning and a rough side for really tough algae marks. The rough side can also be used to remove lime scale build up from the base of the light unit. Cleaning pads should only be used on the inside of the aquarium. It is not recommended to use other algae pads on the biOrb as these may scratch the acrylic.