Yeah, knew it was 6 or 9... something to that extent, it definitely makes a huge difference. I was convinced that I had to get a new skimmer before I changed the water level and pump; but after getting it set up right I'm pulling a ton of gunk every day. My water level in my sump is 9" and so I have a plastic box that it sits on to raise it up to the right level, though I did get a new sump last weekend, so I should go back and try and get it in the ~6" range. I'm not sure if your skimmer returns below water level, but I put a 1" PVC elbow on mine to get the water to not make any noise. However it's metric, so the 1" PVC elbow I had to shave down to get it to fit the outside, inside the gate valve... a little jerry rigged, but cut the noise down a lot.