Two Little Fishies' BettaMag Cleaning Magnet is an even smaller window-cleaning apparatus than the NanoMag. It's designed for use on betta and goldfish bowls or pico aquariums. In small bowls or pico aquariums the NanoMag is so strong it actually moves the whole tank when you try to clean the windows! The BettaMag solves that problem by being sized just right. It’s ideal for glass with a thickness of 1/8 to 1/4 inch. With glass aquariums you need to avoid trapping sand and gravel between the magnet and glass as it will scratch the aquarium. Do NOT use with acrylic aquariums. Patented design by Julian Sprung.