Cloverleaf Absolute Bio Pearls are for maintaining healthy, clean, clear water in ponds and aquariums. Each pearl contains millions of microscopic nitrifying bacteria, and a combination of fast acting bioactive enzymes that rapidly remove ammonia and nitrite. Simply add them to your filter and they will start working straight away. 100% safe to use with all freshwater fish, plants, and other wildlife. Contains 75 pearls, sufficient to treat up to 1875L.