How to stop Sump Drain Gurgle?

[Matt]

I've taken a slightly low-tech approach, which was to cut a 2l pop bottle so that the down-flow was just barely underwater, and it overflows back up and over the side. I cut one side a little lower to allow the water to exit smoothly, and it got very quiet. I can make it almost silent, but I have to let the water make some noise, though, or I get frustrated by the sounds of fans and pumps, and I like water noise better than machine noise. As an added bonus, it brings all the bubbles back to the surface before they enter the sump.