Santa Monica Filtration Hog1 Hang-On-Glass UAS Upflow Algae Scrubber ATS with Green-Grabber Textures Removes nuisance algae, nitrate and phosphate from aquariums By growing in the filter which can be easily cleaned Can't overflow onto your floor, because it is always under water Attached to your aquarium or sump glass with magnets No electrical parts go in the water