Convert a Keg Into a Fermenter!

Cornelius Keg Lid for Secondary Fermenter

Kegs has some really distinct advantages as vessels, in general…

  • They are made from stainless steel
  • They are well built
  • They are pressure capable
  • They are generally well made, many times designed for years-long tough commercial use

How about we convert these into fermenters?

One economical way to do this is to remove the gas post and put a small, tight fitting piece of tubing over the top of the male threads.  Many times such a piece of tubing will also snugly accept an airlock.

A purpose built solution, pictured above, is also available that’s basically a modified keg lid.  That comes with a right-sized stopper to allow you to put an airlock in the modified lid.

Cornelius Keg Fermenter Lid via Adventures in Homebrewing

These lids should work equally well on standard ball lock and pin lock style homebrew kegs.  See: Ball Lock Kegs vs Pin Lock Kegs – What’s the Difference?

Sizing: A five gallon keg isn’t really suitable for a primary fermenter for a 5 gallon batch.  You could use it as a secondary for a full 5 gallon batch, as a primary fermenter for smaller batches (maybe 3 to 4 gallons max) or you could split 5 gallon batches between two kegs.

There are 10 gallon ball lock kegs on the market.  Find one of those and you can do all the same stuff with a 5+ gallon batch.  10 gallon ball locks are difficult to find.  Your best bet is probably ebay.  Try this search, but don’t be surprised if nothing shows up in the search results.

Fun with keg fermenters!

  • Swap the fermenting lid out for the regular lid and use a trimmed dip tube and you can transfer under pressure.  The trimmed dip tube is essential to leave behind trub and avoid clogs.  You could also use William Brewing’s Top Draw Beer Pick Up Tube instead of trimming a dip tube.
  • Ferment under pressure using a Spunding Valve
  • Naturally carbonate in the keg using a Spunding Valve

More Fermentation Related!


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