Adapter gardena fitting 50mm pipe

I need to drain my tank every week.into a 50mm PVC pipe, with a pump.but every time the pump gets air, the pressure changes and my hose flies out of the pipe.now I made an adapter to glue on the pipe, so it's connected only thing needed is a (garden) qd connector with 26mm threat, as far as I know the middle size. you can hit me up for other pipe sizes.