My rockwood popup is sending water out of the overflow when I turn on the pump. Last month I was using a city water hookup and had no problem. Five days ago, I filled the fresh water tank and water was flowing correctly. The next day the pump kept running with little water coming out the faucet, I heard water running outside and saw that it was coming from a plastic tube which I didn,t even know existed but which I think is an overflow valve. Any ideas lou loibl ohio