I hooked everything up and filled the tank with freshwater for a test drive. Upon turning the the return pump on in the sump the overflow pipe is sucking a lot of air. I am running a 1 inch drain pipe and a 3/4 inch return. I tried a bunch of stuff to get the drain to stop sucking so much air, including trying to fit a 3/4 inch fitting on the end of the train pipe and changing water levels. Does anyone have an idea to get it to stop? I was thinking of adding a ball valve in the drain pipe so I can adjust the flow but I don't want to waste the time if it doesn't work. Thanks in advance.