Pawfly Strong Magnetic Glass Cleaner, 2 Scrapers

Glass thickness, not tank size, sets the two sizes here: S holds on glass 1/4 inch thick, and M on glass from 1/4 to 1/2 inch. Each Pawfly cleaner uses a rare-earth magnet, a coarse pad inside the tank and a soft fluff pad outside that wipes water spots off the front. Two blades come with it, one stainless steel and one plastic, and either snaps onto the coarse pad.

Measure the glass at the top edge before you choose, since a magnet sized for thinner glass loses its hold. Non-slip silicone on the edges gives your fingers a grip. The inner pad floats if it comes loose, but do not leave it sitting in the water between cleanings. Acrylic tanks are outside its range.