Function: The bio air-fed sponge filter is perfect for aquariums, providing both mechanical and biological filtration, which can remove waste and maintain clean water for your fish effectively. The bio sponge filter can produce masses of air bubbles, which will help promote gas exchange and increase the level of dissolved oxygen in the tank water. Easy to install or to clean: for installation - just connect the bio sponge filter to the air pump by an air tube. For cleaning - If the sponge becomes dirty, you can remove it and squeeze it using water for the fish. Remember to clean cracked stones regularly. For media: you can add organic media such as gravel, or change it to your favorite media and some polyester yarn. Unique design: is made with a soft sponge material, traps floating debris , and the multi-layer shape increases the surface area to achieve better water and oxygen exchange rate, will be safe for small fish like betta, dwarf cichlid, guppy, killifish etc Aquarium size: recommended 3.5-1.5 liters, you can put it in the corner of the aquarium or hide it behind the plants, suitable for small aquariums or small fish containers frying, such as shrimp aquariums, betta aquariums, goldfish, snails, discus, guppies, fish, etc. Tips: To ensure that the bio sponge filter does not not float, you'd better soak the sponges in your old tank water and squeeze out all the air outside, then let it sit for a few hours while the bacteria settles, then put the filters together and press the sponges into the tank for a few times until there are no bubbles left. 'air. Size: about 4.8 x 8 cm, the diameter of the pipe is about 1.6 cm. Color: black and white Quantity: 4 pieces