This Venturi was designed for high flow to allow you to syphon water quickly. As you can see from the diagram the restrictions are low. After you print the venturi, you should break the short tube out of the center of the base. (only needed for printing) Secondly you will need a hose gasket to form a good seal. Remove the three thin support structures from the input drain on the side. Works great with http://www.thingiverse.com/thing:219628 Once the syphon has been established the the water from the source can be turned off as long as the seal is not broken the water will continue to flow.