Mag Float's 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. Most impressively, you will no longer get wet cleaning off the algae from you glass/acrylic aquarium. Mag Float Aquarium Cleaners will simply float up allowing easy retrieval.