Now you can start gradually opening the screw, maybe an eighth of a turn, so that the bubbles are just above the base of the cup. It isn't unusual for a skimmer to foam a lot when first installed. It will eventually start skimming consistently. I found with the 9002 that cleaning the collection cup twice a week maximizes its performance. Since the reactor is narrow, film build-up makes the foam collapse more quickly than in skimmers with wide reactors. Also make sure the water level corresponds with the data on the unit. It is faded but if you look closely on the narrow end of the skimmer, there is a wavy water level mark.