The output of the pump also has to be moded to fit. The 1/2" pvc is pushed over a piece of 1/2" vinyl tube and heated. Tighten a hose clamp over it so it's just firm, let it cool down and remove the clamp and you'll have a snug air tight fit that can be removed later. Vinyl tube is 3/4" long and the 1/2" tube is 2 1/2" long.
Clinton