Air bubbles in display

[zhewitt04]

I keep getting micro bubbles in my display. I can't find any leaks and there are no bubbles in my sump. This is a new pump and I had to add some fittings and a valve so my question is should I just silicone around the joints and see if that stop the bubbles or do I just add a bead of pvc glue and let it set for a hour and see if that blocks any potential leaks?

[cloak]

How far is the surface of the water in your sump from the intake on your return pump? If it's fairly shallow, every now & then a whirpool might be created, thus injecting a small burst of bubbles into the DT. Just a thought.

[Reefmedic79]

The same can happen at the outlet of the return or the return nozzle is too shallow pulling air into the stream.