I'm sure there are multiple ways to do this that apply to however you have your drain and sump set up. In my case, my sump is in the room behind my tank. When my drain lines come through the wall to go into the sump, I installed a "T" fitting on the PVC with one line going straight down into the sump water and the other side goes straight up and is capped with a small hole drilled in it to vent off the air that gets sucked down the durso. May not work exactly like that for your specific setup, but you can see the general idea. I had 90's on there originally, just to see what it would do, and had huge glorping bubbles in the sump. With the setup as above, I just get a little fizz.
HTH