After our extensive basement remodel, we had a plumber install a new sump pump and battery backup pump and a "quiet check valve." I told him I wanted a quiet and safe system. He installed what "they normally install." The main pump looks to be a solid, cast iron pump. The backup looks plastic. I'm having noise issues. 1. There is often a slurping noise when it kicks in. 2. After the pump shuts off, there is about 15-20 seconds of gurgling that sounds like water flowing back down into the pit. That seems like a long time for water to flow back a couple of feet. 3. The backup pump, though hard to see, looks like it is not resting on the floor of the pit, but rather is jammed between the main pump and the edge of the pit so it is suspended off the floor. Is any of this normal? Is any of it problematic? Is any of it contributing to excessive noise? I am going to have the plumber back, but since he installed it, he is going to say what he did is fine.