Versatile: sponge filters provide mechanical and biological filtration. Air jet chamber creates tiny air bubbles to increase oxygen solubility. Biosponge: Biosponge has undergone extensive testing in its design and manufacture. The cotton filter element is made of high quality material and is more durable than any sponge filter element on the market. NO NOISE: The filter makes no noise during operation, just rinse it in the tank and squeeze the sponge while cleaning. Wide range of applications: up to 55 gallons, especially suitable for feeding small freshwater fish (such as petunias, guppies, scale insects, etc.), or frying in hatcheries, spawning ponds and rearing ponds as the filter produces very little current, it is almost impossible to use fish through the filter. Reliable customer service: you want to give our customers a good shopping experience.