Venturi Tube...help?

[london_kev]

Hey all,

wondering if you can help me in explaing how a venturi tube work? been seaching online but no luck in how this works am not getting any bubbles any help?

 

[LostInTheArk]

Hi if it is the small cap type thing you need to slightly screw it and turn the outlet so its pointing down wards if you have not worked this out already. I'm sorry if you already have done