Add this auto shut off devise with check valve to your aquarium RO/DI water filter system and it will sense the pressure from your float valve and instantly shut down the water to the membrane. The reason this is so important is that the filters in the system need to stay submerged in water. Shutting the system on and off with each use allows the water to drain from the system and dry out the filters. It takes way too much of your time in performing water changes and top offs just sitting around waiting for the container to fill. With this device installed on your filter system you will no longer waste tons of water and more importantly you will no longer waste time. Just turn on your RO/DI system and go about your daily activities! Installation is a snap with the quick connect fittings built in.