It will be a work in progress. You need to adjust the airflow to a point where your getting skimate, but not to much, and not to little.
It's a work in progress because your trying to find the right amount to run the skimmer to take care of your bio load... but not to much more, and not to much less.
If you do this for weeks and can't get it right.... Then slow down your feeding schedule and try again.