I have a RSM 250 with a rear sump and am using a Deltec 500 skimmer. Although the skimmer was working okish I have never been overly impressed with the performance, so after messing with sump level and lowering it 1 inch it made a huge difference to the skimmer performance. It's now doing a great job and producing almost black skimmate that smells really bad, I couldn't be happier with performance now.
This is just a POI of how important the amount of water the skimmer sits in your sump and thought I would share my findings.
I guess it's no different than tuning a car to get the best performance possible.
