Having trouble with millions of tiny air bubbles

[free4mudden]

I am having trouble with tiny air bubbles coming thru my returns. I am using a wet/dry sump that is spit into 3 compartments, with openings at the bottom of the walls, without the bio balls, skimmer, a mag 12 in the sump. My return line (3/4")comes up out od the sump to the top of the tank then splits into 2 lines. I have tried closing the shutoff valves part way and that doesn't work. Today, I put some live rock in the sump and that isn't working. Anybody have any ideas?

 

[GobyWanKenobi]

Is your pump away from any type of aeration, turbulence? I would also check for potential leaks in the return line plumbing mainly the joints which may not have been fully sealed.

 

[free4mudden]

I have checked everything.