The KW Reactor™ 300 creates saturated kalkwasser solution every time the feed pump is switched on to replenish evaporated water. Gentle mixing is achieved with a rotating sprinklerhead that is “powered” by the pressurized water feed Specifications Capacity: Use with up to a maximum of 1 cup calcium hydroxide. Aquarium Size: One reactor for aquariums up to 300 gallons (1135 Liters). Recommended Pump Size: ca. 200 - 300 gal/hr (760 - 1140 L/hr). The pipes automatically reduce the flow to a small stream. Connection for Hoses: 1/2 inch (12.7 mm) i.d. The inlet and outlet flexible 90° fittings rotate to suit your installation. Approximate size: height: 15.25", width: 5". reactor diamater: 4"