Safe and effective-- Sponge filters provide both mechanical and biological filtration, provide the ideal location for bacterial colonization and the sponge traps larger waste particles mechanically cleaning the water without trapping baby fish Dual 10 Layer Sponge Design - it quickly established a bio-filter and extra oxygen, two sponges means more surface area for beneficial nitrifying bacteria to colonize and faster cycling, keeps your aquarium water super clean and crystal clear Easy to use-- Use an air hose to connect one end to your air pump and the other end to this filter. The water flow outlet tube on the sponge filter is adjustable so you can change the direction and height of the water flow Specification-- The hose can be adjusted between 19.5cm and 27.5cm in length, the filter canisters have a capacity of 100ml, the sponge is 4.8cm x 8.4cm, suitable for a fish tank of 210 L maximum. Application-- Comes with 2 suction cups to stick to the glass, can be installed anywhere, it can also be used as a pre-filter or secondary filter; perfect for shrimp aquariums, betta aquariums, breeding aquariums, turtle aquariums, goldfish, discus, crayfish, fry, baby fish or other fish.