The HydroGEN™ Pro is the only water cooled CO2 generator. Water cooling can remove 86% of the heat produced by burning propane and has many features not available in any other CO2 generator on the market. The unit can easily be used in a closed-loop system with a small chiller and reservoir, or you can connect directly to your home water supply and drain to storage for reuse in your garden. This optional valve (used in place of a pump) is designed to be installed in a pressurized water line and to be controlled by your CO2 monitor. This is a high quality solid brass valve designed for years of service. The valve has 1/2 in NPT outlets that can be used with your existing plumbing or you can install on 1/2 in hose barbs to make the connection. You will need either a pump or a valve but not both.