Provide a safe environment for your freshwater and saltwater friends with API Aqua Essential Aquarium Treatment. Tap water often contains chlorine, chloramines and ammonia which can cause gill and tissue damage, breathing difficulty, stress—and even death for your fish. This special treatment instantly removes chlorine and chloramines, and neutralizes heavy metals. It also removes toxic ammonia, nitrites and nitrates to restore a healthy aquatic environment. This highly-concentrated water conditioner makes it easy to maintain a clean, beautiful aquarium