Making a few assumptions, however these tips may help.
I assume your
skimmer is creating the bubbles, if so how is your
skimmer returning its water back to the
sump?
One tip that works is run the
skimmer water output over for example a stepped Perspex sheet, I used this in the past to remove micro bubbles from a display tank, that had a
HOB skimmer, that was introducing bubbles.
Imagine a flat per Perspex sheet, with ridges stepped all the way running from left to right like the steps on a ladder, I made the ridges using beads of silicone sealant. Running the return water flow over this will beak the micro bubbles.
Next tip, that has helped me in the past, is if you only run one return pump try running two at half the flow rate of the single you are running so if you have a 6000 litre per hour single return, replace that with two 3000 litre returns, it gives the bubbles slightly longer to dissipate in the
sump before being returned to the tank but you are still moving the same volume of water.
Probably help more with a better description of your setup.
Cheers
Nath.
