Sera Magnet Cleaner Floating removes algae and other dirt from the aquarium glass, including hard to reach corners. It easily fits to the aquarium, and you can clean the glass without getting your hands wet! The cleaning brush floats meaning that it is easily retrievable should the brush become detached from the handle during cleaning. Suitable for glass aquariums up to 4mm thick. This product is NOT recommended for use on acrylic or plastic aquariums.