I've always felt my waterline is a little high. I mean when I use a tooth brush brushing rock if I put any sort of move in spill water over. Just curious what it should be. Not sure if I can even adjust it. I guess I can with a slowly return pump. I can turn it down but I feel it's not that powerful. I use my cor 20. And I have it maybe at 60-75 percent. I'd have to look.