What causes the majority of bubble issues is break in and depth/air setting.
1) Unplug the skimmer, adjust the depth so between 1/4 and 1/2 of the front intake under the cup is submerged, too deep causes more bubble problems. Open the air all the way. Plug it back in. Work with depth first, then close the air as little as possible. Closing the air increases the water flow so the bubbles are traveling faster and further and more exit.
2) Make sure the skimmer is not in a path of strong flow, if the compartment is high flow bubbles will be drawn out by the current.
3) Give it time, I just set up a 9012DC on my home tank, for about 5 days I had some bubbles exiting the bottom, in time this will stop as it breaks in.