bro im running on the same skimmer, but i dont have such prob.
- You can try putting the skimmer furthest away from the return pump.
- Place a sponge like one of the bro here said at the output of the skimmer or at the sump flow direction to block bubbles.
- Try to adjust the water level, this might be the problem. Maybe place the skimmer higher or lower.
SM201 imo is a very good skimmer, been performing very well since I bought it.
Hope it works for you.