Take your basic 2L pop bottle, remove the label and rinse it out. Cut enough of the top off that your
skimmer return lines will fit inside of it but that some of the curve remains. Cut one or two 1/8" wide x a few inches long slits about 3" up from the bottom.
Stick this in your
sump with some cheato in it. A little ball will be all you need to get started. My
skimmer sits outside of my
sump but however yours is arranged put the
skimmer return lines into the top of the bottle. The water goes into the bottle and through the cheato which tends to trap the bubbles. It your pump pushes more water than the slits will handle (as is likely) it will just overflow the top of the bottle and back into your
sump. But the water will have passed through the cheato trapping bubbles plus it has to travel back up the curve of the bottle trapping more bubbles and I never see micro bubbles in my
DT.
