Tap water contains chemicals, such as chlorine, chloramines and heavy metals which are harmful to fish. So, tap water must be treated before adding fish. API makes several products to help ensure proper water conditions for optimal fish health. Visit our Easy Care Guide step Start Up & Change Water to learn more about what products to use and when for creating ideal water conditions for your fish. TAP WATER CONDITIONER instantly removes chlorine and neutralizes chloramines. It also detoxifies heavy metals in tap water. TAP WATER CONDITIONER is super concentrated. One ounce treats up to 600 U.S. gallons