The Filter Medium Is Suitable For Aquarium Sponge Biochemical Filter PRODUCT details 【Optimize biological filtration】The device of the aquarium contains media, which is for removing certain chemicals and in the water produced by fish. 【Safe material】The bio- is made of PVC, which is light enough to keep its shape, never degrade, wear-resistant, reusable, and has a long service life. It is also easy to handle and clean, can promote gas exchange and increase the dissolved oxygen content, and the design is porous. 【Large openings】Our biosphere allows oxygen-rich water to through them without restriction. This provides a certain amount of oxygen and oxygenation. 【Shape conversion】The round shape makes the biosphere easy to adapt to any filter. The filter can promote gas exchange, reduce and control harmful ammonia and nitrate, while increasing the of dissolved oxygen. 【Unlimited lifespan】Considering that these bio-balls are made of high-density polypropylene, they will degrade, so they can work year year. The package includes: A bag of filter balls