Tetra Pond FilterStart biologically activates the pond filter after winter or when establishing a new pond, extending the time between cleanings and water changes. It contains a carefully selected mix of highly active nitrifying bacterial strains that break down pollutants and reduce sludge. Thanks to live cultures of nitrifying bacteria, the levels of harmful substances such as ammonia and nitrite in the pond are reduced. Special cleaning bacteria decompose organic materials like fish waste and leaves. It prolongs the lifespan and operation of pond filters and the time between pond cleanings. Additionally, it improves water quality and prevents decay. It has a purely biological-natural effect.