I recently moved into a house and know very little about sump pumps. I just noticed that the sump pump operates even when it's clear outside. The sump pump goes on, the water goes out (I assume since the water level in the sump goes down), but a moment later the water level in the sump goes back up as the water streams in thru the sides of the sump, and the pump comes on a few moments later. This doesn't seem normal. Shouldn't the water go out and the sump be empty? What should I do? Does this work require a plumber?