Hi. I was running a Big Blue for my return pump. I wanted more GPH as it was only doing 146 gph after the long return tube. I got a Jebao DCT 12000 which was very clean. Doesn't look used but I think it was. I notice on the Jebao that when I turn up to where only two more circles remain unlit that I can hear it. There is a high whine. I turn it down one and cannot hear it. I don't like messing with pump once installed. Should the whine be concerning? Its not terrible but it is audible.