The venturi on all skimmers is the same, the 9010, 9015 and 9020 have the same pump, it is only how far you open the screw that determines the airflow. I suspect you have the skimmer too deeply submerged so water is being sucked into the air intake and restricting the airflow. Normally with the foam extractor is everything is properly installed you get a good result with the air screw open 6-7 turns.