GrowoniX EX400 - 400 GPD Reverse Osmosis Filtration System400 Gallons per day of pure RO water filtration Designed to flow 17 gallons per hour of pure RO water, with an astounding 2: 1 ratio High flow rates and water savings never before seen in a package so affordable and durable. Utilizing the most efficient membrane technology in the world, and equipped with a steel pressure gauge. A manual flush valve allows you to clean the membrane, purging out pollutants that could otherwise add buildup to the system.