Bio balls are suitable for both freshwater and saltwater tanks. A great help in restoring the natural water quality and providing the most suitable living environment for your fish. This product can be used in a variety of filters, put it in the appropriate position of the filter. Characteristics: The organic balls are cooked at high temperature. Full of rich variety of natural elements, essential minerals and trace elements. Encourages the growth of biological colonies and contains large amounts of good bacteria. A great help in restoring the natural water quality and providing the most suitable living environment for your fish. Suitable for freshwater and saltwater tanks. Reduces ammonia and nitrate levels. Any problem, please contact our store without hesitation. Honor to serve you! Specification: Name: Aquarium filter media ball Color yellow Material: quartz Ball diameter: 21mm Package information: Package size: 20 * 15 * 8cm / 7.87 * 5.90 * 3.15in Package weight: 420g Plastic