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Yeast Starter Blow Out!

Hey All,

First time poster!

So I prepared a yeast starter this morning and encountered an interesting outcome. I followed the yeast starter instructions as I have in the past. Everything seemed alright until this afternoon when I went to check on my starter. I gave it a quick swirl to aerate it a bit and it was so carbonated that the foam stopper blew off and it spilled out everywhere.

I’m guessing the stopper wasn’t letting any co2 out? Is this bad? Should I not use my starter?


Here is what it looked like shortly after the blow out…

You should use the starter its should be good but in the future do not use that stopper you should use aluminum foil loosely so that co2 could escape

Foil FTW.

I’ve had a few explosive bubbling events when I’ve walked by and given the flask a swirl.

two easy swirls is better then one big swirl…

I had my first starter bllow out when I made my last batch. I made a Dead Ringer IPA. Using a 1056 smack pack. First off I have never had a smack pack expand so quickly or to such extent. I thought that the packaging was going to give out, it was that tight. But other than that variable I just made my starter like normal and pitched my yeast when the wort was cool enough, put it on a stir plate and went to bed. Next morning I checked it and the foam stopper didn’t completely blow off but it was cocked just enough to let some of the blow off out. What a mess.

That was the only episode like that I have ever had. I will tell you that my IPA fermented like a monster. Blow off tube on my fermenter was much appreciated on that batch.

I use a foam stopper and have had several blowouts. No big deal. I spray it with a little starsan and pop it back in. No issues.

P.S. Get a stir plate. It will help cut down on over foaming. Of course when you make a 2L starter in a 2L flask… that’s another story.

Foam or foil, it shouldn’t make a difference. Just use a bigger vessel for the starter. Gallon milk jugs (thoroughly cleaned and sanitized, of course) work well.

A 500 mL starter is tiny, FWIW.

Thank you everyone for the posts! I ended up pitching the yeast last night and today I’m getting some good activity.

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