Reef Octo 110SSS Microbubbles

Initial:

Skimmer has been running for 8 months, it's broken in.
Water Level is 8->8.5 inches from the bottom of the sump

Problem:
Tons of microbubbles from the output.
I do dose Vinegar(carbon)
When I break down the skimmer, and clean it throughly, removing pump etc, it minimizes the bubbles, but after a few weeks the microbubbles return en mass and flood the display.

Are there any other adjustments to make? The skimmer is functional and works well otherwise.

Thanks!