Help me understand what happened. Have a pump with a "built in" check valve which is basically a rubber disk that fits inside the discharge and is held in place when the discharge pipe is attached. I inadverently left the rubber check valve out when I first installed it and upon plugging it in, it blew the bottom screen off. It seemed to be pushing air instead of sucking water. I disconnected, reinstalled with the rubber check valve and all functioned properly after that. Just curious what happened by leaving the check valve out at first. Did it allow air into the pump by not allowing a tight connection?