Air bubbles in Powerhead

[BBoley24]

I have my powerhead totally submerged and yet airbubbles still shoot out... what is the science behind this?

[GobyJohnKenobi]

Assuming that you aren't talking about cavitation caused when the impeller starts spinning when the pump is energized, I'd say that any other bubbles coming out of a powerhead are from the bubbles that form on the underside of the powerhead and eventually find their way over to the intake strainer.

If you see bubbles coming from a powerhead that has been running for a while, just take a turkey baster and direct a stream of water along the underside of the pumps housing. Should dislodge them.