Bubbles in the spray bar are not an issue that effect performance unless they fill the bar all the way and no water can come through. There appears to be a intake on the outflow piece ( the black thing above the where the water comes out.) That should be adjustable so you can try adjusting that to reduce any air coming into the outgoing water.Bought this filter over a week again and been working perfect but today it’s getting bubbles in the bar like trapped air and I can’t get them out , any ideas what to and yes it is low enough at the correct level