First Defense for reef and nano aquaria was developed to help fish and corals adapt to new environments by assisting their natural immune system. First Defense also promotes healing, repairs wounds and supports the immune system with nutrients and immunstimulants. First Defense is great to add to shipping bag with you are accilimating you new corals, after fragging and also to your dip solution. Changing the environment of a fish causes stress that robs corals/fish of essential nutrients and can weaken their immune system. First Defense is scientifically designed to provide stress relief and support the immune system, helping corals cope with stress due to bagging and shipping from the store to your tank, water changes, new fish additions, disease treatments, and other environmental changes. Corals and fish are subject to many stressful events before becoming comfortable in your aquarium. For instance, they were shipped in bags to the store and then chased around the tank, netted and bagged before you took them home. Many times fish are not fed much before shipping so that their waste does not pollute the shipping bag but this can further weaken their immune system. As with people, a weakened immune system means a greater chance of the coral or fish to become sick with a bacterial infection. The mixture of immunostimulants and nutrients in First Defense have been demonstrated to help support the immune system of fish so they can fight off diseases. First Defense also contains buffers to help maintain the water pH. Further, First Defense detoxifies heavy metals and removes chlorine and chloramines. For Saltwater aquariums. 16 ounces treats 960 gallons.