Octopus Skimmer Issues

[ShAgMaN]

Does anyone know Octo skimmers well?

I have an older 150 model that is bubbling too much. The air line is fully open (restricting it only makes it worse) and the adjustable return tube is all the way down.

Thing is, if I remove the o-ring on the stationary return tube I'm barely getting enough skim - but if I put the or-ring back on it skims way to wet.

Additionally, I took the skimmer out recently for cleaning and everything looks fine.

Any suggestions?