I'm a new homebrewer and I just finished racking my second batch of beer, a one-gallon Irish stout from extract.

My first batch came out great, and made six delicious bottles. But, when I took the carboy out to rack the beer this time, about half of the original volume seemed to be missing - only enough for three bottles. There was also an unusually large amount of trub on the bottom, way more than I had in my first batch.

Both batches were the same kind of beer, from the same supplier, and I tried to follow the exact same steps.

What could cause this discrepancy?

1 Answer 1


Gratz on your second brew!

This is just speculation from the limited info. Detailed steps and ingredients will help in the future.

If there is actual liquid volume missing from the fermentor, then it left in the form of foam out the airlock or someone drank it. If there's no mess, then the later

Here are some common causes of large beer stealing trub beds. Trub takes up space and reduces your final yield, but doesn't reduce total volume in fermentor.

  • large cell count from high gravity beers
  • high floculant yeast
  • misuse of whirlfloc or Irish moss. This should be left behind in the whirlpool. Often overdosed.
  • fruit additions adding plant material
  • dry hopping or transfering boil hop additions material to fermentor. Can be limited by proper use of hop bags and boil finnings.

I'm sure there are many more, this is just what comes to mind.

  • Thanks for the answer! I didn't make any unusual additions like Irish moss or fruits, and followed the exact same recipe with exactly the same ingredients as my first batch. There was no mess in the locker where I keep my carboy. The carboy had an airlock on top (I don't put any vodka or sanitizer in the airlock, though). The large amount of trub on the bottom seems suspicious to me.
    – Bill
    May 12, 2016 at 14:29
  • @Bill was the level of the carboy low? Or was there just more trub than usual? Fyi you need some sort of sanitizer in an airlock they don't work without liquid, if it was dry an infection could make more bio mass increasing in amount of trub. May 12, 2016 at 15:24

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