Yogre
Cheesehead Reefer
You're right it's not airtight, but I gotta figure the vast majority of air is being drawn through the lid. I'd try that before I'd start using outside (dry in the winter) air directly into the Venturi.
As you said, if the Venturi is going to be constantly clogging you're not much ahead of where you were with the needle wheel.
As you said, if the Venturi is going to be constantly clogging you're not much ahead of where you were with the needle wheel.