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Red cap on airlock - on or off?

Hello - I’m thinking the red cap stays on, but then how can anything escape? So maybe the cap is suppose to be off - but then whey even have a cap. That’s what’s going on in my head.


The cap is meant to be left on. If your airlock is like the ones I have, there should be four pinholes in the red cap that lets air (and C02) through. In any case, it should be able to vent around the edges of the cap.

Thanks Marty - appreciate it!

Glad to help!! :cheers:

If you lose the red cap a piece of aluminum foil works just as well. Oh and yes it is designed to stay on, let the CO2 out but protect the water from evaporating. BTW some use cheap vodka in airlocks instead of water or sanitizer. It keeps it sanitary and if a little gets sucked back into the fermenter it is no big deal.

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