skimmer noise

My skimmer makes this horrible noise that literally keeps me up at night! (Its in my bedroom) It only makes this sound when the air valve is open. When it is closed, the skimmer is dead silent. (See attached video) It doesnt sound like air induction, it sounds like its coming from within the...

I have a aqua medic skimmer but when I got it the pump was faulty. The Venturi was part of the pump So I've removed the pump (and also the pumps Venturi as a result) and have plumbed the skimmer body directly into my manafold. To get air into my line I've drilled a hole into some fittings and...