Tetra AlgoStop Depot eliminates both brush and thread algae and prevents further algae growth. The shape-stable tablets contain highly effective algicides with a broad spectrum of action and a depot active ingredient for the controlled release of the active substances over a period of approximately 6 weeks. When used correctly, it does not harm fish, aquatic plants, or microorganisms. Please use the algae treatment carefully and always read the label and product information before use.