Need help with sump design

You don't have to have microbubbles in your system for the water to be oxygenated. My drain sends a ton of bubbles and not just the micro kind into my fuge and as no detrimental effect.

As far as microbubbles getting into the DT, my skimmer and my return pump are in the same section in my sump and I never have problems with bubbles unless I have to disconnect the RP. The returns I have one pointed toward the center of my tank and the other pointed to the top of the water toward the center of the tank which it breaks the top of the water when the wave is not in center.

I don't know of any particular articles on oxygen exchange but i recommend reading through these articles. I have probably read all of them at least once. They ,for the most part, are very readable without too much super technical stuff making them easier for the "hobbyist" marine-biologist in all of us.

And that is the great thing about this hobby, the more you learn the more you realize you don't know.