Two Little Fishies Kalkwasser Stirrer/Reactor has a patent-pending design by Julian Sprung. Designed with an 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. Mount on the back of your aquarium or below your tank. Includes check valve and flexible connection fittings that rotate 180� to suit your installation.