Author: Matt Del Fiacco
From cheap plastic buckets to stainless conicals that emulate the pros, the fermentation vessel options available to brewers these days is quite vast and can lead to some difficult decision making. While higher end vessels offer myriad features such as the capacity for closed fermentation and pressure transfers to avoid oxidation, they cost upwards of 25 times more than their less expensive counterparts that don’t have all the bells and whistles.
I started brewing when I was a college student, a time when both space and money were rather limited. Having embraced the importance of fermentation temperature control, I repurposed a mini-fridge as a chamber and brewed smaller batch sizes because I couldn’t fit anything larger than a 3 gallon/11 liter carboy. As I brewed more, I learned about the perils of cold-side oxidation and found appealing the options afforded by some of the new stainless fermenters on the market, but I couldn’t justify dropping that kind of cash given my situation at the time.
Fairly soon after my introduction to brewing, I transitioned from bottling to kegging my beer. I didn’t build a fancy keezer with a bunch of expensive faucets, but rather picked up the bare essentials that would allow me to skip the hassle of bottle conditioning– a CO2 tank, regulator, gas and beer line, picnic taps, and of course, a few used corny kegs. It was around this time I read of someone who had adapted a corny keg for use as a fermentation vessel. Constructed of durable stainless steel, capable of holding relatively high amounts of pressure, and outfitted with gas and liquid posts to allow for closed transfers, this seemed an ideal alternative to the stainless fermenter options at the time.
After making some minor adaptations to a keg, I gave it a shot and was immediately hooked. I’ve been fermenting in kegs for nearly 4 years at this point and often receive questions from folks interested in doing the same. My hope in penning this article is to cover both the very simple process of converting a corny keg to a fermentation vessel as well as thoughts and recommendations based on my personal experience, and discuss.
CONVERTING A CORNY KEG TO A FERMENTER
The beauty of fermenting in a corny keg is that the process of putting it together is less about actual building and more about adapting what’s already there, which doesn’t take much. The first and most obvious step is to get a corny keg, of which there are two main types– ball lock and pin lock. While ball lock kegs are more popular among homebrewers, I went with pin lock because they’re less expensive and have easily distinguishable gas and liquid posts. I prefer buying used and reconditioned kegs, as they cost markedly less than new kegs, plus you can get packs that further reduce the price, and having more than one keg fermenter is very convenient.
Once the keg is acquired, it’s important to disassemble it and give it a good cleaning. Removing the posts is quite difficult without the right socket, there are both pin lock and ball lock versions that make removal a cinch.
It may take a bit of force at first, but the posts will eventually loosen up and easily unscrew from the keg, at which point they can be soaked in the cleaner of your choice and scrubbed to remove any icky bits.
With the posts removed, the long liquid dip tube can be pulled out of the keg in preparation for the next step. In order to lower the risks of clogging during transfers, it’s important to reduce the length of the dip tube by about 1 inch/25 mm so that the bottom rests above the trub line.
While the tube can be cut with a hacksaw or Dremel, an inexpensive stainless tube cutter makes the task incredibly easy and clean, so I recommend it for those who might be making multiple fermentation kegs.
After cutting the tube and cleaning all parts of the keg, simply put it all back together, making sure everything goes in the proper spots. I like to mark the kegs I’ve converted to fermenters by wrapping the handles with electrical tape.
As every brewer knows, yeast produce CO2 during fermentation that needs to be released from the fermenter. Since fermentation kegs are completely closed with no airlock hole, you’ll need to fashion a blowoff tube using a 4-6 foot/1-2 meter gas line and a gas disconnect (make sure to get ball lock if that’s your jam).
Finally, in order to transfer the beer out of the fermentation keg and into a new keg, you’ll need to make a jumper using two liquid disconnects (again, ball lock if that’s what you’re using) and a 15 inch/38 mm length of beer line.
And that’s all it takes. The keg is now ready to be used as a fermentation vessel.
FERMENTING IN A CORNY KEG
Prior to using a fermentation keg, it’s crucial to ensure the lid o-ring isn’t dried out or cracked, as this can result in CO2 leaking out of the keg lid. I always start by applying a small amount of keg lube to the o-ring to ensure a good seal.
The beauty of stainless is that it’s very difficult to melt, so if you’re into no chill brewing, you can rack hot wort directly to the fermentation keg and allow it to cool before proceeding. Regardless, once the wort is racked to the sanitized keg and the yeast is pitched, the lid gets attached, the fermentation keg gets placed in the chamber, and the blowoff tube is put in place with one end submerged in clean water or sanitizer.
Once fermentation is complete, the beer can be cold-crashed if one so chooses, after which it gets pressure transferred to a fresh serving keg. With the liquid jumper line going from the fermentation keg to the serving keg, a small amount of pressure from a CO2 tank pushes the beer from one to the other.
One thing I love about fermenting in kegs is the ability to naturally carbonate the beer toward the end of fermentation, a method referred to as spunding, which involves racking the beer to new a keg when it still has a bit of fermentation to go then attaching a spunding valve.
After racking the beer out of the fermentation keg, I give it a good cleaning by removing the posts and dip tube, soaking them and the keg in cleaner, then rinsing and leaving to dry. It couldn’t be easier!
I’ve been fermenting in corny for years and absolutely love it. In addition to being a very affordable alternative to higher end fermenters, it opens up a bunch of options including closed transfers to reduce cold-side oxidation, purging the serving keg of oxygen using naturally produced CO2, and spunding for natural carbonation. Kegs also have a smaller footprint than most other fermenter types, though they are a bit taller, something one should consider based on their chamber dimensions.
One noted drawback to fermenting in corny kegs, seeing as they only hold 5 gallons/19 liters of beer, is that the maximum recommended batch size is 4.5 gallons/17 liters, which is definitely worth the trade-off for me. Also, while one could figure out a way to siphon out of a keg, the process of transferring beer is a lot easier with external CO2, which requires a tank and regulator. While it is an added expense, even with the keg, it’s likely cheaper than other stainless options.
One question I’ve received quite a bit over the years has to do with serving beer from the keg in which it was fermented. Is this possible? Absolutely, I’ve heard from a number people who have done it, but I don’t because transferring the beer off the trub to a fresh keg is so easy.
Corny kegs remain my fermenter of choice and I truly believe they’re an excellent option for brewers interested in reducing the risk of cold-side oxidation, or even the newer brewer looking to upgrade fermentation vessels in an expensive way. Cheap, simple to use, easy to clean, and effective. What else could a brewer ask for in a fermenter?
If you have any thoughts about this DIY fermentation keg or have experience fermenting in kegs yourself, please do not hesitate to share in the comments section below!
Support Brülosophy In Style!
All designs are available in various colors and sizes on Amazon!
Follow Brülosophy on:
FACEBOOK | TWITTER | INSTAGRAM
If you enjoy this stuff and feel compelled to support Brulosophy.com, please check out theSupportpagefor details on how you can very easily do so. Thanks!
