I have a couple of tunze nanostream 6055's that are located a couple of inches below the water line. It doesn't constantly happen, but maybe every five minutes one of the powerheads makes a vortex sucking in air and spreading bubbles all over the tank. An easy fix would be lower the pumps, but because they are located in the front of the tank, I don't want to do that. I'm wondering if anyone knows of a mod/shroud that would work to alleviate this problem.