micro bubbles

[reefsahoy]

question,
i'm getting micro bubbles in the return to the tank and there are no bubbles in the sump. if i restrict the input to the pump i get more bubbles. if i open back the input and restrict the output the bubbles are less or depending on how much restriction i get no bubbles. i've replumbed the entire system more than once so i seriously doubt that there is an air leak in the plumbing and i've been to a lfs and restrict their input to their pump and no bubbles. any ideas?

 

[ReefWreak]

Cavitation? Best answer I can think of... And you would be suprised at how difficult it can be to really really seal in plumbing.

Good luck getting rid of it though. I know it can be frustrating. I've given up on that long ago...