Premium Grade Liquid Filtration Medium Breaks down food residues, ammonia, and nitrite biologically Provides a stabilization area for beneficial purification bacteria Creates a biologically active environment Toxic hazardous substances such as ammonia and nitrite are constantly formed in aquarium water. Sera Bio Nitrivec, a product of Sera's biological technology, contains millions of purification bacteria, through which a stable biological balance is quickly and reliably established, leading to the continuous breakdown of the formed toxic substances. The added volcanic mineral rocks work to remove pollutants, effectively bind clouds, and provide a suitable stabilization area for purification bacteria. For healthy, clear, and biologically active water. Fish can be added after 24 hours when combined with Sera Aquatan! Volume sufficient for: 50 ml - 125 liters / 33 US gallons 100 ml - 250 liters / 66 US gallons 250 ml - 625 liters / 165 US gallons 500 ml - 1,250 liters / 330 US gallons 2,500 ml - 6,250 liters / 1,650 US gallons 5,000 ml - 12,500 liters / 3,300 US gallons