tunze 9410dc

Tunze 9410 Protein skimmer. Probably the best skimmer I’ve ever owned. Upgraded tanks and it’s not big enough. $200 shipped

I don't know what I'm doing wrong with my skimmer, I've had a Tunze 9410DC skimmer for about 3 months now, and everytime I do a water change i also clean out the cup and scrub it down with the provided brush the skimmer came with. I do a 10 gallon water change every week on a 115 gallon aquarium...