Bought this skimmer used and it worked great for the first several months. Started getting a lot of micro bubbles, so I did the standard cleaning of the air hose and nipple, but still got bubbles. Cleaned the pump still nothing. Tried adjusting the water level and still nothing. Has been running this way for 2 weeks. I am still getting good skimate and the bubbles are not making it to the main DT, but I would rather this wasn't happening.

