Diito what was said before, you have to adjust it so that the waterline just barely touches the emergency (middle) drain pipe - or about 1/2 inch from it. This will quite all the gurgling. However, if you go too far and it flows down the emergency pipe, it will be noisy again. So it has to right in between.
I think it is fixed as all I can hear is the water in the sump. The runoff on top is very quiet!
I think that the culprit was that the valve was stuck half way and wouldn’t go completely clockwise.