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Venting over carbonated homebrew beer

venting home brew beer gushers

Have you ever had a beer gusher


They damn well suck. You casually open your beer and whoosh! There's beer foam all over the bloody place. 

Why did this happen? 

The fizz is the result of over carbonation. 


There could be a few of reasons for this. 

1. You bottled too soon and fermentation continued.
2. Your beer is infected by bacteria and they have overproduced on the CO2
3. You added too much sugar at bottling time.
4. You served your beer too warm

All these factors you have a strong degree of control over. 

If you've bottled too soon, you should have taken a final gravity reading and determined that matched the kind of beer your making and that you had the same reading two days in a row. 

If your beer is infected, it's quite likely you didn't clean and sterilize your equipment and bottles properly. I've said this a million times on these pages, you got do the basics and do them well

And if you added too much sugar, you might want to rethink your practices. If you batch primed, how much did you add? From my experience 60 - 80 grams of sugar is enough for 23 litres of beer. Any more and you will quite likely get gushers. 

If you added sugar individually, then you clearly added too much sugar. I used to use a good amount of sugar, now I try and use half a tea spoon of sugar. It's more than enough. 

If you want a consistent and safe measure, you can always consider using carbonation drops when bottling your brew

Can you fix gusher beers by venting?


Yes, you can, kinda. 

Let's be clear though - if you've got gushers because you've got a bacteria problem, your beer is rooted and you'll need to tip it out and sterilize the bottles very well. 

What you can do is vent your beers individually. The technique is that you gently pry the bottle cap open so that only a part of the cap is exposed, let the CO2 escape and then quickly recap. You need to all of this before the gusher occurs! If you are clever you should be able to use your bottle opener to both open and close the cap with the same action. 

If you are really brave you might be able to remove the whole cap and replace with a new one as this will allow more CO2 to be released. It will be messy though - perhaps a second pair of hands will be able to help. It's possibly not worth the potential wastage!

It will be a long, painful process and you'll likely need to repeat the venting on each bottle if there is a lot of built up pressure. 

I have found in the past that the colder the beer is, the less likely it is to gush or be to fizzy or foamy. Thus I would recommend that you leave your beers in a fridge for 24 hours before attempting this little rescue job of your beer.

A wee risk to bear in mind 


Over pressurized beer can explode. And then means glass can explode. I've seen the result in my man shed - green glass everywhere and the dank smell of wasted beer. 

If your under pressure beers are that much of an extreme you should ask yourself is it safe to vent? While beer bottles are generally tough, the risk is there so I'd recommend you use gloves and a good pair of safety googles or glasses

What's the lesson here then? 

Use less sugar when bottling beer

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