[mkj]

I have baffles, it has nothing to do with that for me.

It's because I have a small sump return section and my return pump is pulling lots of water which makes small turbulence in last return chamber. In hindsight, I would have make my return section slightly larger but I was trying to max space. My next sump will have an adjustment for this problem. There is a point where return section is too small for how much water is being pulled through, just don't ask me where that point is.