I have a better picture attached.
The dual 1-1/2 PVC lines comes to the top of my sump from the returns. From the bulkhead I go to a 1-1/2 90 then to a 1-1/2 to 2" adapter and then to a 3" tee with a 2" leg.
Sections of 3" PVC are cut for the top and bottom of the tee, and a 3" cap is placed on top of the Tee with a few tiny holes drilled so it can exhaust the air escaping.
Basically, the increase in PVC size from the bulkhead slows the water down. Of course I didn't give it much room to slow down as I was limited. At the tee the air bubbles want to rise to the top water level, they burst and the air escapes through the hole drilled in the PVC cap. Some of the bubbles still get forced down with the water as you see. I could slow my return pump down some, but I don't get any bubbles returned to the tank as it is. They don't make it to the bubble trap in the sump. As you can see, if they do make it out of the bottom, they all rise pretty quick right around the 3" tee, and there they stay.
If you take the cap off of the 3" PVC tees, you should see the turbulence and hear all the noise this thing eliminates.
I stumbled across this idea on a google search for a reverse durso.