The KW Reactor 300 is designed with the upflow principle to achieve the most efficient use of Kalkwasser. By pushing top-off water upward through the calcium hydroxide, it automatically mixes it to achieve a supersaturated kalkwasser solution. Very convenient design that can be mounted hanging on the back of the aquarium or below the aquarium. Includes ball valve for regulating flow and flexible connection fittings that rotate 180 degrees to allow a perfect custom fit.