Those who know us, often hear us saying that there are almost as many ways to brew beer, as there are homebrewers. The reason being that just about everyone has a slightly different collection of equipment than the next person, which, when all is told, makes a slightly different beer. In this regard, running your fermentation is no different.

At first thought, some people might wonder just what this is supposed to mean. Afterall, we just put the wort into the fermenter, add the yeast, and the rest just happens by itself with little or no intervention. As Dave Miller so succinctly puts it “Homebrewers make wort. Yeast makes beer”. Just look into some homebrewers’ basements and closets, however, and you’ll see that there is a plethora of variations to the basic themes. Rather than go into details about each and every of these variations, we’ll discuss the basic themes, and touch on some of the variations. We’ll also discuss some of the factors which come into play no matter which of the methods you choose.


Fermentation Methods

When it comes to running the fermentation, there are two basic themes which are used almost universally by all homebrewers. The first of these is called single-stage fermentation, while the latter is called double-stage fermentation. Although these are very similar in most regards, each does have its own advantages and disadvantages.

Single-Stage Fermentation is an easy, reliable way to brew good beer. It is called Single-Stage because the entire fermentation process takes place in one vessel: either a carboy or a food-grade white bucket. The homebrewer bottles the beer once the fermentation has run its course. The advantage here is primarily that it is a bit less work than double-stage fermentation. The disadvantage is that your beer sits on top of the sediment (trub and spent yeast), which can impart an off-flavour to your beer if left too long. However, common wisdom states that it is perfectly fine to leave your beer on the sediment for up to 5 weeks without suffering such a fate, which means that it is perfectly suited to most of the beers that people brew. As an extra margin of error, we usually recommend leaving the beer in the primary fermenter for at most 3 weeks. If the beer is still not ready to bottle after this time, it should be racked into a secondary fermenter.

Another disadvantage of the single-step is only of concern if you want to propagate yeast from one batch to the next. The problem here is that a lot of what initially sediments out in your primary fermenter is not yeast, but rather is hop residue, coagulated proteins, and other material. Although you could certainly wash your yeast to remove this material, it is easier if you do not have to worry about it in the first place.

Basically, just about anything but a real Lager can be brewed by this method, unless you want to reuse your yeast.

Two-Stage Fermentation is so-called because the first, vigourous stage of fermentation takes place in the primary fermenter, after which the beer is siphoned (racked) into the secondary fermenter to finish fermenting. After sitting in the secondary fermenter for 1 or more weeks, the beer is of course bottled or kegged. Although slightly more involved, this is the method used by many homebrewers who feel they feel it is better to get the beer off the sediment ASAP. This is a muchly debated topic in the homebrewing realm, though most brewers agree that it is perfectly safe to leave your beer on the sediment for up to 5 weeks with no ill effects.

Another plus of two stage fermentation is that it usually allows for less sediment in your beer bottles, since sediment is racked off twice, rather than just once. And as mentioned, it is easier to reuse yeast from one batch to the next when using this method, since the protein, hop residue and other undesirable material was left behind in the primary fermenter when the beer was racked to the secondary. So mostly all that is left on the bottom of the secondary is yeast.

Using a Blowoff

Although most homebrewers use a food-grade white plastic bucket for a primary, some prefer the use of a glass carboy for the job because it allows the fermenting beer to blow off a lot of tannins and other residue which they say may impart undesirable flavours to the beer. This is another highly debated topic in the homebrewing world, and personally we do not notice a difference with or without a blowoff, so we do not use one anymore. One disadvantage to a blowoff is that a volume of beer may be lost, depending up the yeast used, and other ingredients, as well. Usually this will be 500ml to a litre (a pint to a quart), but in some extremely cases (like if you pitched too much yeast) it could blow off several litres.

One other potential disadvantage, and it is a pretty major one if you happen to get bitten by it, is that when using the blowoff system there is a chance that your blowoff hose will get clogged up with junk, causing pressure to build up in your carboy. If you are lucky (if you can call it that), your stopper will blow out of the top of the carboy, possibly putting a hole in the ceiling, and blasting beer over the entire room. If you are unlucky, the stopper will be in there really tight, and your carboy will explode quite violently, potentially causing serious bodily injury. To avoid this, most people recommend using an extremely large diameter hose for the blowoff. Best to get a 2 inch (or so) hose which fits over the entire mouth of the carboy. We have had clogged hoses when using smaller diameter hose, and have been lucky to catch it in time to simply replace the hose with a fresh one. It doesn’t take too long of a search on the newsgroups to find someone who’s actually had a carboy explode, so please be careful.

Fermentation Vessels

Although any suitably-sized food-grade container can be used as either a primary or a secondary, most homebrewers use a food-grade white bucket for the former, and a carboy for the latter. We generally switch back and forth between the two with no real rhyme nor reason other than perhaps our mood at the time. Other possibilities include the use of a stainless brewpot as a primary, a converted pop keg as a secondary, or even one of the new plastic or stainless conical fermenters as a uni-tank. primarysecondary

The chart below, compiled by Steve Rosenzweig in the rec.crafts.brewing newsgroup, and used here with his permission, details the advantages and disadvantages of the various materials used for different fermenters :

Glass Stainless Plastic
scratch resistant excellent excellent depends on use
oxygen barrier excellent excellent poor over long storage
cost medium high low
sturdiness fragile excellent good to excellent
typical use pri/secondary pri/secondary primary
potential flavour unlikely unlikely possible
ease of cleaning acceptable easier easiest


Conical and Uni-tank

A conical is a fermenter previously used only by the professionals, but is seen more-and-more among the arsenal of homebrewers. If you are a fan of Drew Carey, then you’ve probably seen one by now in his garage. They are tall cylinders with an inverted cone attached to the bottom of the cylinder. The cone has a (steep) 60 degree slope to it, to facilitate the removal of sediment from the valve at the bottom of the cone. Bascially that’s the key advantage of a conical, that it allows for the removal of sediment without actually having to transfer the beer. Another nice feature is that there is typically a lot less work involved in making a batch of beer, since there is so much less transferring, and lifting of heavy fermenters.

Until very recently, unitanks were available only in stainless steel, which made them extremely expensive even for smaller ones. There are, however, now several marketed mainly to homebrewers, which are made out of food-grade plastic, and are therefore extremely affordable. Even stainless conicals are coming down in price dramaticaly such that many homebrewers now own them.

A unitank is a type of conical fermenter which can hold pressure, and can thus be used for primary and secondary fermentation, as well as conditioning which comes next. Often fermentation will even be conducted under pressure , and when it is complete the vessel is pressurised and cooled to condition the beer.

If you are considering investing in a conical fermenter, there are some very important factors you have to take into consideration, since they require significant re-thinking of your typical brewday. First and foremost, a conical fermenter tends to be an extremely stationary object, so getting your beer into it may be an issue. Many brewers conduct their brew day in one location, fill their fermenters there, and then physically move it to another location for fermentation. This is not feasible even with a smaller 5 gallon conical, so some thought is in order on how to get the beer from point A to point B.

The obvious solution is of course to brew and ferment in the same location and thus eliminate the problem in the first place, but that is not always possible. If not, then another solution is to fill a normal plastic fermenter and carry it to the conical and dump it in. This will aid in aeration, but all that carrying defeats part of the benefit of a conical : i.e. less work. The solution we came up with was simply to run some 20 feet of copper tubing between the brew location and the conical, and let gravity do the rest. See our photos for details.



Most people who begin homebrewing, know that temperature is a crucial factor in fermentation. Unfortunately, this “knowledge” which they have usually gotten from old-time brewers tells them to ferment their beer at a warm temperature. No disrespect is meant to the old-timers out there – they just didn’t know any differnt. In fact, the truth is that ales should ideally be fermented at or slightly below room temperature (60-75F or 15-22C), and lagers should be fermented well below that (35-55F or 2-10C). Although some specialty yeasts like Belgians and Hefeweizen generally prefer to be fermented above 75F/24C and even as high as 82F/28C.

The reason that most ales get fermented below 70F/20C is that yeast produces a lot of by-products when it ferments sugars at a higher temperature. In fact, the higher the temperature, the more by-products it produces. Almost without exception, all of these produce flavours which are not desirable in beer. Esters and others produce flavours often described as fruity, banana, or even clove. In the case of the aforementioned Belgian and Hefeweizen yeasts, these flavours are still produced but the yeast has adapted to do so in a controlled fasion which is quite enjoyable to most palates. Though in the vast majority of beers brewed with normal yeasts, these flavours are quite unpleasant.


Fermenting a lager is the topic of a book in and of itself. In fact, Gregory Noonan’s “New Brewing Lager Beer” is exactly the book you should have. But we can at least get you started.

The key to a lager is that it must be fermented at an extremely low temperature, and since most yeasts will fall dormant at these cool temperatures lagers require a special type of yeast. The majority of lager yeast strains today are descendants of the yeast which the founders of the Carlsberg Brewery in Denmark stole from brewmasters in Bavaria. The centuries old Bavarian tradition of storing beer in cool ice caves to help it keep better well into the warm summer months slowly caused the yeast to mutate into a strain that actually thrived in these cool conditions.

But why would we want to ferment at such low temperatures? Well, as we know, yeast produces more by-products at higher temperatures, and these by-products have a lot of flavour to them. By fermenting your beer at extremely low temperatures we dramatically reduce the production of these by-products such that they are well below the threshold at which human beings can taste them. This allows the flavours of the malt and hops to come through in the beer.

Even though lager yeast has evolved to thrive at low temperatures, a lager fermentation takes a lot longer to complete than an ale fermentation. As one might expect, the cool temperatures slows things down quite a lot. And not only does it take longer, but it also requires a lot more yeast for a healthy fermentation, than what is required for an ale. About 3 times the amount of yeast, in fact. So a huge yeast starter must be made if using liquid yeast – enough to produce a good half cup of yeast slurry. The only dry lager yeasts that we know of are those from DCL, and up to 50g should be used for a good lager fermentation.

The ideal way to pitch a lager is “cold pitch”, or add the yeast once the wort has been chilled to fermentation temperatures – usually around 8C-10C or 45F-50F. Less yeast is required if you pitch at room temperature and then chill the young beer to the desired fermentation temperature over the next couple of days, but this will produce an amount of the undesired flavours caused by the yeast by-products which will be produced at those higher temperatures. Decent results can still be obtained by warm-pitching, but most lager brewers agree that cold-pitching is really the only way to go.

Do not expect the fireworks from a lager fermentation that you get from many ale fermentations. The cooler temperatures keep things relatively subdued and you may not see more than about 1 cm or half inch of light kraeusen on top of your fermenting beer. You can also expect the fermentation to last up to a week or even longer. Once primary fermentation has completed you should transfer to a secondary fermenter and then lower the temperature down to 5C / 40F where you can leave it for up to a month.