Tetra FilterActive adds highly effective live bacteria and thus promotes permanent biological activity in the aquarium. Tetra Filter Active+ accelerates degradation of pollutants like ammonia and nitrite+ optimises cleaning performance of the filter for clear water+ maintains a biologically balanced aquarium+ promotes good water parameters and well being of fish+ boosts filtration after filter maintenance and water changes+ for all freshwater aquariums+ dosage: 5 ml on 20 litres of aquarium water