Features: 1.Good acid resistance and stability, not corroded by other acids. Strong hydrophilic, will not influenced water quality change. 2.Quartz ball can eliminate toxic ammonia nitrogen and nitrite nitrogen, spherical structure in the water area is large, large surface area can be used for nitrifying bacteria growth. 3.Quartz ball, hardness, easy to clean and reuse. 4.Quartz anoxic space in the interval can cultivate anaerobic bacteria. The anaerobic bacteria convert the organic matter into organic matter that can be biodegraded. 5.Used for upper filtration, bottom filtration and outer filtration of fish tank. 6.Suitable for fresh water, sea water. Specification: Item type: Fish Tank Quartz Stone Material: Quartz Color: white Recommendation: The quartz stone is placed in the mesh bag and placed in the filter tank. Recommended to wash once every 3 months, achieve better water purification effect. PackageList: 1 Bag x Filtratlon Quartz Stone1 x Mesh Bag