Fluval Peat Granules provide an all-natural way to soften aquarium water and achieve the pH levels required for breeding and rearing certain tropical fish. Peat contains humic acid tanning agents and trace elements that are essential for various life processes. Highly concentrated for maximum effectiveness this product is recommended for fish that prefer soft acidic water. Key Features : An all-natural way to soften aquarium water and achieve the pH levels required for breeding and rearing certain tropical fish Contains humic acid tanning agents and trace elements that are essential for various life processes Highly concentrated for maximum effectiveness Recommended for fish that prefer soft acidic water For Fluval filter models: 106 206 306 406 FX5 105 205 305 405 104 204 304 404 500 g (21 oz)