serabio nitrivec is a liquid filter media with a special mixture of different high quality purification bacteria for aquarium water. sera bio nitrivec prevents the enrichment of ammonia and nitrite. When using sera bio nitrivec fish can already be added after 24 hours.sera bio nitrivec+ premium class liquid filter medium+ breaks down food remainders, ammonium and nitrite biologically+ provides settling area for useful purification bacteria+ creates a biologically active living environmentPlease use a good water conditioner (like sera aqutan) for removing chloride from the aquarium water.Dosage for sera bio nitrivec:Add 10 ml sera bio nitrivec per each 25 litres of aquarium water.