Fermenters

 

Modified hybrid fermentation vessels in 45-bottle wine coolers

 

Introduction

Fermentation vessels (FVs) or simply 'fermenters' are where wort is held as yeast ferments it into beer. Fermenters are available in a variety of shapes and sizes made from different materials, the most popular of which today include plastic, glass, and stainless steel.

One of the top questions we are asked is "What is the best fermenter?". That's not a question that can be easily answered as any vessel can be used to make excellent beer. Brewers should choose a fermenter based on what best fits their process, not because they've been misled into believing that one style of vessel will make better beer than another. This is especially true at smaller homebrew batch sizes where the weight of the wort and vessel geometry do not come into play.

Remember that some of the best beers in the world are made in fermenters that range from simple open vats to advanced enclosed conicals and unitanks. Figure out your process first, then choose the fermenter that allows you to correctly implement that process.

In this guide we break down some of the most common fermenters and list their pros and cons so that you can choose what's best for you. We also explain what we use, why, and how we modified the fermenters for our specific process.

Ramon pitches yeast into an open fermenter at Anchor Brewing of San FranciscoRamon pitches yeast into an open fermenter at Anchor Brewing of San Francisco. Anchor open ferments all of their beers: Ales in square, deep vessels and lagers in wide, shallow 'coolship' fermenters. Image (c) anchorbrewing.com

Deschutes Brewery assistant brewmaster Chris Dent flanked by rows of conical fermenters in their state of the art 2 bbl pilot brewing systemDeschutes Brewery assistant brewmaster Chris Dent flanked by rows of conical fermenters in their state of the art 2 bbl pilot brewing system. The system allows Deschutes to play with variables to find what makes beer better. Image (c) bendbulletin.com

 

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Plastic food-grade buckets

7.9 gallon plastic food grade fermentation bucket

Plastic food-grade buckets are by far the least expensive fermenters available. Most brewers will start with buckets given the low cost, resilience, and ease of use. 

Pros:

  • Very easy to clean due to the large removable lid.
  • Very inexpensive.
  • Lightweight.
  • Reasonably sturdy.

Cons: 

  • Easily scratched and therefore more difficult to sanitize effectively (scratches give bacteria a place to grow).
  • Plastic is a poor oxygen barrier so plastic fermenters should not be used for long term storage or conditioning. During fermentation this is not an issue as the bucket is under positive pressure as CO2 is produced and expelled. Once fermentation is done the beer should not be left for extended periods (a few days is fine).
  • Limited to smaller sizes, usually under 8 gallons.
  • Cannot be pressurized.

 

Glass carboys

Glass carboy

Glass carboys are popular amongst brewers who wish to store their beer for extended periods after fermentation is done, given that glass is impermeable to air. The weight and fragility of glass make them more difficult (and dangerous) to use. 

Pros:

  • Scratch resistant so can be effectively sanitized.
  • Excellent oxygen barrier so can be used for long term storage or conditioning.
  • Inexpensive.

Cons: 

  • Very fragile, and very slippery when wet. If you choose to use glass carboys, we recommend carrying them in milk crates (or similar) when full. Carboy handles are available but should never be used to lift a full carboy. Very hot water or wort should never be added to a glass carboy as it may weaken or crack. For this reason we never recommend purchasing used carboys as you have no idea how they were abused.
  • Can be more difficult to clean due to the small opening.
  • Limited to smaller sizes, usually 6.5 gallons or less.
  • Difficult to measure wort temperature during active fermentation. The thicker walled glass is actually a fairly good insulator so stick-on strip thermometers do not always work well (as they do on thin-walled stainless vessels). More direct contact is required such as can be had with a Tilt digital wireless bluetooth hydrometer & thermometer.
  • The clear nature of glass carboys means that the fermenting beer is susceptible to skunking from light (sunlight and LED / fluorescent bulbs are the most damaging). An old t-shirt or towel should be used to cover the carboy. 
  • Cannot be pressurized.

 

Conical fermenters

Conical fermenter

Cylindroconical tanks (usually just called 'conicals') have a slanted, cone-shape bottom which, among other advantages allows brewers to easily remove yeast for disposal or repitching.

Pros:

  • Scratch resistant (if stainless) so can be effectively sanitized.
  • Excellent oxygen barrier (if stainless) so can be used for long term storage or conditioning.
  • Very sturdy.
  • Available in just about any size imaginable.
  • The slanted cone-shape bottom coupled with a bottom valve allows sediment to be dumped so that the vessel can be used as a post-fermentation brite tank for clarifying, or for yeast to be harvested for reuse without transferring (racking) first.
  • Ability to clean in place (CIP) through a CIP spray ball and pump.
  • Many have multiple bottom outlets, including slightly higher valves that allow samples to be drawn without inclusion of yeast that has settle in the bottom cone.
  • Some include integrated heating and cooling systems for automatically controlling fermentation temperature.

Cons: 

  • Considerably more expensive than plastic buckets or glass carboys.
  • Takes longer to clean given the many parts and fittings.
  • Cannot be pressurized.

 

Unitanks

Unitank

Unitanks (short for 'universal tanks') are typically conicals that are built to withstand higher pressures (usually 15 PSI or more). The ability to ferment under pressure allows higher fermentation temperatures to be used without the usual production of off-flavours / esters. For example, it's possible to brew lagers at room temperature (instead of 50F) and suppress the fruity flavours that would normally be introduced when lager yeast is used at such a high temperature. Unitanks still allow for fermentation at standard atmospheric pressure for ales where fruity esters or other yeast derived flavours are desired. Higher pressure also allows carbonating directly in the fermenter before packaging. Pressurization can also simplify performing closed transfers and filtering directly out of the vessel, the latter being an option mostly used by professional brewers who wish to skip using the vessel as a post-fermentation brite tank for clarifying. 

Pros:

  • Usually the same as conical fermenters listed above.
  • Can be pressurized which reduces the time to go from grain to glass, especially with lagers.

Cons: 

  • More expensive than conical fermenters and considerably more expensive than plastic buckets or glass carboys.
  • Takes the longest to clean given the myriad of parts and fittings. Make sure they're features you need as you'll be cleaning them after every use regardless! 

 

Hybrid solutions

Brew bucket stainless steel fermenter

Hybrid fermenters such as the Brew Bucket Stainless Steel Fermenter (shown in the picture above) combine many of the benefits of plastic buckets, glass carboys, and conical fermenters into one. Pros and cons will vary depending on the features the manufacturer wishes to implement.

Pros:

  • Easy to clean due to the large removable lid.
  • Scratch resistant (if stainless) so can be effectively sanitized.
  • Excellent oxygen barrier (if stainless) so can be used for long term storage or conditioning.
  • Very sturdy.
  • Most are available in sizes larger than plastic buckets or glass carboys.
  • Some include optional heating and cooling systems for automatically controlling fermentation temperature.

Cons: 

  • More expensive than plastic buckets or glass carboys (but less expensive than conical fermenters and unitanks).
  • Most do not have a true bottom valve to allow brewers to easily dump sediment or to remove yeast for reuse without transferring (racking).
  • Most cannot be pressurized.

 

Controlling fermentation temperature

Not all fermenters include integrated heating and cooling systems for automatically controlling fermentation temperature.

To control temperature with simpler fermenters such as plastic buckets or glass carboys, brewers have a wide variety of options available including building a home made fermentation chiller, using a regular fridge or freezer with a temperature controller to override the built in temperature dial, or a wine cooler or beverage center (no external temperature controller required if the built in range is acceptable for fermentation). If you have a location available to you where the ambient temperature remains steady at (or just slightly below) the fermentation temperature, then temperature control is not required. All will produce first rate results if used correctly and the temperature remains steady.

During active fermentation yeast can throw off heat, resulting in a wort fermentation temperature that is slightly higher than the ambient temperature. This is especially true with more active ale fermentation. If you are fermenting in a fridge or similar where the wort temperature is not being measured and controlled directly, you may need to set your temperature slightly below the desired wort fermentation temperature. Stick-on strip thermometers are a surprisingly accurate method for monitoring the wort temperature on thin walled stainless steel fermenters and plastic buckets. They are not ideal for monitoring fermentation temperature in glass carboys as the thicker wall is actually a fairly good insulator.

If fermentation above ambient room temperature is required, some form of heating is required. A temperature controller driving a low wattage incandescent lightbulb inside a fridge or freezer (turned off) works well. For an example see our Belgian Super Saison recipe.

 

What fermenting system do you use?

Modified hybrid fermentation vessels in 45-bottle wine coolersModified hybrid stainless fermenters in fridges. No external temperature controllers required.

We use a hybrid of a hybrid solution (😉) with two modified 7 gallon Brew Bucket Stainless Steel Fermenters in wine fridges with the shelves removed. This setup best matches our brewing process and results in the least amount of cleaning for us.

Why two fermenters? Having two identical setups allows us to experiment with different yeasts, dry hops, and processes. We normally make 12 gallons of wort and split it across the two fermenters.

The fridges we use are available as 45-bottle wine coolers or 124-can beverage centers which can be set from 39 to 64F, allowing a wide variety of beers to be produced from lagers to ales without any additional modifications (no need for external temperature controllers).

The lowest 39F setting is used when we need to chill wort below ground water temperature, the lowest temperature we can achieve with our counterflow chiller. A few hours in the fridges set to 39F is all it takes to bring the wort down to pitch temperature. This is mostly used for chilling wort to 50F when fermenting lagers (as our ground water rarely gets that cold), or when chilling hop forward beers as quickly as possible to lock in late addition hop flavours and aromas.

The highest 64F setting may appear a touch low for some ale strains but remember that this is the ambient (set) temperature, not the wort temperature. During the initial stages of an ale fermentation the wort will be a few degrees higher than the ambient temperature. So if we wish to ferment in the high 60s we set the fridges to 64F during the first few days and the actual wort temperature will be a few degrees higher. Once the most active fermentation is complete the fridges are turned off and the temperature slowly rises to the ambient room temperature (70-72F), perfect for finishing off most ale strains. We rarely ferment higher than ambient room temperature.

How did you modify your fermenters?

We replaced the standard (flat) lid on the stainless steel fermentation buckets with a domed lid with a 3" Tri-Clamp (Tri-Clover) fitting as it provides more room for krausen and makes it easier to use an aeration wand and to add dry hops.

A 3" Tri-Clamp (Tri-Clover) cap and 90 degree hose barb are used to connect 1/2" ID silicone tubing (make sure to use a hose clamp) as a blow off hose that is placed in a jar half full of water, creating an airlock. A hose like this is much less likely to clog compared to a standard airlock and also lessens the height of the vessels allowing them to fit in the fridges.

Breakdown of stainless steel fermentation bucket domed lid partsBreakdown of stainless steel fermentation bucket domed lid parts

(A) Domed lid with a 3" Tri-Clamp (Tri-Clover) fitting
(B) 3" Tri-Clamp (Tri-Clover) cap
(C) 90 degree hose barb
(D) 3" Tri-Clamp (Tri-Clover) clamp
(E) 3" Tri-Clamp (Tri-Clover) gasket
(F) Stainless steel smooth-band worm-drive hose clamp (5/8" to 1-1/16" clamp diameter range)
(G) 4 foot piece of high temperature food-grade silicone tubing (1/2" ID 3/4-7/8" OD) 

Plastic fermentation buckets in fridgesPlastic buckets also fit if a small stand is used to raise them above the compressor hump at the back of the fridges. These stands were built from scrap pieces of 2x4 and painted black.

Early models of the stainless steel fermentation buckets included square silicone inserts for the legs that were overly soft. After about a year of use the edges sheared off due to the soft nature of silicone. We replaced these feet with harder plastic leg inserts.

Brew bucket old silicone feet vs new plastic feetOld silicone leg inserts (damaged) on the left, new plastic leg inserts on the right

Why don't you use conicals or unitanks?

So why don't we use conical fermenters or unitanks? The short answer is that it's more work / cost and the beer wouldn't be any better. The long answer: Our process doesn't benefit from the additional features like fermenting under pressure or dumping yeast, we prefer to keep cleaning as simple as possible, and we're not in a hurry. Let's look at these one at a time:

  • Additional features: The ability to bottom dump sediment or yeast after fermentation is the most obvious feature we are missing by not using conical fermenters or unitanks. It's not a feature we are interested in as:
    • We mostly perform single vessel fermentations which go direct to keg (rarely using a brite tank for clarifying).
    • We rarely reuse yeast. Most of the time we make a fresh yeast starter as it helps ensure the highest level of consistency from batch to batch. Keep in mind that yeast can still be collected from any vessel after the beer is transferred. The bottom dump would simply allow it to be done a few days sooner if the vessel is also going to be used as a brite.
  • Fermenting under pressure: Being able to pressurize a unitank and brew lagers at room temperature without refrigeration may appeal to some. For us the cost of our simpler fermenters with refrigeration is considerably lower than unitanks without refrigeration. Depending on the ambient and ground (chilling) water temperatures there are times where we would still require some form of chilling anyway. If you like to chill or crash after fermentation then some means of chilling will definitely still be required. Just like temperature, pressure is yet another variable that will affect the flavour of the beer so our process steps would need to be adjusted to compensate. Our process and recipes have been honed over the years to produce results we like with the equipment we have on hand for fermenting at atmospheric pressure, so fermenting under higher pressure is not something that is high on our radar. 
  • Faster grain to glass: Related to the last point, fermenting under pressure with a unitank can reduce not only the fermentation time but the conditioning time as well (as less flavours are produced to begin with). This reduced time is most apparent with lagers. Pro brewers looking to maximize profits by reducing process timelines should definitely take a good look at pressurized fermentation to minimize grain to glass time. Homebrewers tend to be less concerned, so how quickly beer can be turned around has never been a concern for us.
  • Additional cleaning: Conical fermenters (and especially unitanks) have lots of additional parts and features. All must be carefully disassembled, cleaned / sanitized, and reassembled after each use. While a clean in place (CIP) spray ball with pump setup can simplify this process, don't underestimate the time required to disassemble and reassemble. Why spend extra time if these additional features will not be used?

But that's just us. Don't assume that our method is best for you. As mentioned previously, look at your brewing process and then choose the equipment that best matches that process. Keep in mind that your brewing process may also be different from one beer to the next so ensure the equipment you choose is flexible. See the 'Notes / Process' section in our various recipes for examples on how process can vary.

 

What size fermenters do I need?

Krausen right up to the lidKrausen right up to the lid from a batch of Electric Hop Candy

Fermentation, as well as the initial aeration or oxygenation before yeast is pitched, produces a lot of foam (krausen) so a fermenter at least 20-30% larger than the volume of beer you wish to produce is recommended. 

Trying to ferment 5 gallons of wort in a 5 gallon fermenter will invariably result in a portion of the wort being blown out, which means you'll end up packaging less. Nobody wants a keg that starts off only 75-80% full! In the case of top fermenting ale yeasts that blow-off will also contain a lot of yeast which we really do not want to lose. We want our yeast busy making beer, not reproducing and throwing off flavours.

Some yeasts are especially problematic in regards to the amount of krausen they produce. For example, Wyeast recommends 33% of headspace for their 3068 Weihenstephan Weizen yeast and it's understandable as that yeast produces a krausen unlike any other.

The Brew Bucket Stainless Steel Fermenters we use are fitted with a domed lid with a 3" Tri-Clamp (Tri-Clover) fitting which increases the headspace volume beyond the rated 7 gallon volume to approximately 8 gallons, perfect for 5.5 - 6 gallons of wort. We rarely have krausen enter the blow off hose at the top of the domed lid.

 

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Pictures / Videos

The fermenter related pictures and videos below are from brewing different beers over the years. Hundreds more available in our recipes. Interested in seeing what we're brewing right now? Follow us on Instagram for pictures and videos of our brewing activities as they happen.

 

For hundreds more fermenter pictures and videos see our recipes.