airlock question from a newbie

[faustino123]

Just started my first brew. It is the Festival Razorback IPA.
I am a complete novice and have a very novice question.
The airlock - should I keep the red lid on it, or off?

I thought the purpose was to let CO2 escape but in all the videos I watched they kept the lid on.

 

[Vossy1]

Welcome to the forum F :thumb:
The little red push on cap should really be on, C02 can still escape past it as it's not airtight, it's meant to prevent large things from entering the air trap, flies etc. It can be left off if you want

 

[faustino123]

thanks for clearing that up for me.

 

[bobsbeer]

As V1 says, it's a dust cap to stop dust, flies, etc contaminating the airlock water. I use water in mine, but some do use vodka as that will kill any germs/bacteria if they get in, and it glugs back into the FV.