Product Introduction: This product is a pneumatic filter specially designed for aquarium users. Its design imitates the circulation pattern of nature, allowing the aquarium to form the same microbial filtration as in rivers, lakes, and oceans. The biochemical cotton in the filter box can prevent water from turning yellow and smelly. The nitrite bacteria in the filter bottom box can break down the remaining bait and fish in the aquarium. The remaining fish bait can provide nutrients to plankton and plants in the aquarium, forming a food chain. Instructions for use: Connect the filter to the air pump with an air tube, and then place the filter at the bottom of the aquarium. Turn on the power of the air pump and observe whether the bubbles at the air outlet are normal to confirm the normal operation of the filter.