The airlock’s purpose is to let carbonation out and not let anything else in. So if it doesn’t fit perfectly on your container, that’s okay!
We have a couple tips if your jug is a bit too small for it:
1. Detach the rubber stopper from the plastic airlock. Put the rubber stopper in your bottle, and push down hard. Then, stick the plastic airlock back on top.
2. Separate the rubber stopper from the plastic airlock. Then, put the rubber stopper in boiling water to make it more pliant. Leave it there for about 30 seconds — it should be able to stretch/ squeeze into the neck of your container afterwards.
Just be careful there’s not any boiling water still in there when you handle it!
The airlock on the right is a bit tight, but it forms a seal so it's perfect!
And if it’s just a bit too big:
1. Go ahead and secure it on with a layer of duct tape or electrical tape. As long as you can get it to form a seal, you’re golden.
2. If your container is still too big, you don't need to use the airlock. Just rubber band on some clean cheesecloth or a coffee filter to the top of your container to protect anything from getting in, while allowing carbonation to escape.
A brilliant seran wrap solution for a bottle that was just a bit too big.