Biochemical sponge filter provides biological filtration to the aquarium, helps to stable water quality.Increase the oxygen solubility in water. Working noiselessly. Good permeability, easy to clean. Equipped with a base, placed directly at the bottom of the fish tank.Perfect filters accessories for your tank and aquarium. note:1. Soak the sponge in the aquarium water for 5 minutes before use, by doing this help nitrifying bateria colonise easier. 2. Always use aquarium water under room temperature to rinse clean the sponge, never use hot water. 3. It must be used through connecting the air pump Color: As Shown Material: Acrylic Package Contents: 1 x fish tank filter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.