Can you control the flow of your return pump, i.e. do you have a valve on the return line to slow it? I think you need to find the sweet spot flow wise (may take a while) so the overflow level stabilizes. Also, I turned my overflow line parallel but just below my waterline in my
sump and put a tee on the end. So the water goes down when it reaches the end and any bubble go up to the surface of the
sump. That really quieted it down. Checkout the first few pages of my journal for some photos.
