Adjusting skimmer properly

[Michael]

Question from a newbie who has read a lot.
--Is it okay to have your skimmer output directly into your tank? I find that on my Venturi skimmer with a mag 12 pump, I get a lot of tiny bubbles in my Fish only 75g tank. If I turn the Mag12 down with a gate valve, the protein skimmer doesn't perform as well as it should.
--I have also tried to regulate the air input into the skimmer.

--any suggestions?

Thanks.

Michael