hi,
i also encounter the same problem with the weipro skimmer, my is 2012 with a 1500 aquanic pump and not foam collected after many days.so i change to aquanic3000 and raise the water level( inside skimmer ) toward the neck of the connected cup. boy,the scumb is thick greenish and smelly in the cup and beneath it as well.

trust me it work prefectly.

triggermen.