Originally Posted by Paul_Aris
I wonder where you find the right size gromet?
I found mine at the local Ace hardware store. They are usually in with the specialty screws and electrical items. Ours has an aisle with all these types of things in little boxes on slide out trays with various sizes. I believe I used the 5/16".
I also found these online
You could also drill a larger hole and use a carboy cork with a hole already drilled for the airlock. Whatever you have on hand.