Mag Floats powerful rear earth neodymium magnets enable the easy removal of algae. By dragging the Mag Float on the outside of the tank, the Mag Float on the other side of the glass/acrylic surface follows, scraping off the algae with the pad. What does this mean for you? To put it simply, you will no longer have to get wet hands or algae covered fingers from cleaning algae off your glass or acrylic aquarium walls. If for any reason the inner magnet should get detached, dont worry! Mag Float Aquarium Cleaners will simply float up allowing easy retrieval. Since the release of the revolutionary original, Mag Float has expanded to a number of unqiue variants that resolve a far wider range of aquarium cleaning needs. The Mag Float 20 features a rounded magnet, bringing the easy clean power of the original to any round or bowl shaped aquarium. The Mag Float Plus Float contains a bigger magnet and scraper for easy coverage of large aquarium tanks.