I have a
super skimmer 125 (Coralife) that does a pretty good job. One thing that i've wondered for a while is about it's "burping". Basically, this skimmer has a return line that goes into the bottom of a square plastic cup (meant to minimize bubbles in the sump) which has a foam pad in it. As the skimmer operates, bubbles seem to build up in the return cup and then release. This happens about every 20 - 60 seconds. The negative result is that the foam in the chamber of the skimmer drops about 1".
Hope this makes sense to you that have this skimmer.
The pic I attached is from a while ago but it gives you a visual on what I am referring to.