Safe Material: This aquarium sponge filter is made of high quality plastic and sponge, non-toxic and environmentally friendly and eco-friendly sponge, no harm to fish. Improved Water Quality: The pores of the sponge filter have a large surface area for aerobic bacteria to proliferate. By cultivating nitrifying bacteria, you get excellent biological filtration in your aquarium. In addition, your aquarium water will stay super clean and crystal clear. Easy Installation: The water drain hose on the sponge filter is adjustable so you can change the direction and height of the water flow. Compatible with 2 suction cups, can be installed anywhere, easy to hide on the back wall of the aquarium, and can also be used as a pre-filter or secondary filter. Removable Sponges: You can easily remove the sponge from the filter to clean or replace it. Use tank water instead of tap water to clean when changing the water. Simply rinse and squeeze several times until the water runs clear. Widely used: