Aquarium double head bio-sponge filters, great for adsorbing the stain and fish feces, breeding the colony of nitrifying bacteria. Works with oxygen pump can increase the solubility of oxygen in water. Features: Double head sponge filters for Filtration and Oxygenation. Adopt for bio-sponge filters, easier for adsorbing the stain and culturing the colony of nitrifying bacteria. Increase the solubility of oxygen in water when it work with oxygen pump(not included). No noise, working quietly. Suitable aquarium size: 80-100cm/ 31-39in. Specifications: Material: Spong & Plastic Parameters Detail: Note: Before using it, please soak the filter in the original water of the aquarium for 5 minutes, for culturing the colony of nitrifying bacteria easily. As to clean the filter sponge, the cleaning water must be the original water of the aquarium, do not use hot water or fresh water. Package List: 1 * Biochemical Filter 2 * Sponge 2 * Suction Cup