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Pick Your Fermentor Part II: Advanced Fermentor Choices

If you’re ready to upgrade your fermentor in either size or value, longtime homebrewer Jester Goldman has suggestions to help you make the best decision for your goals.

Jester Goldman February 03, 2017

Pick Your Fermentor Part II: Advanced Fermentor Choices Primary Image

In my last article, we covered the relative merits of HDPE plastic buckets, glass carboys, and PET carboys. If you’re willing to make a larger investment, though, there are some more solutions that offer additional benefits. If you’re perfectly satisfied with your current system, it’s probably not worth the extra cost, but these alternatives can reduce how much air your beer gets exposed to, and some can offer a more “professional” brewing experience.

Corny Keg Fermentation

Stainless-steel trumps plastic and glass. Like glass, stainless-steel is easy to sanitize and prevents oxidation, but it’s lighter and much sturdier. The cheapest entrance into stainless steel−fermenting is to use 5-gallon (19 l) soda kegs. It’s even more affordable if you already have some spare corny kegs sitting around.

There are a few ways to repurpose a keg as a fermentor. The big issue is providing pressure relief, especially during primary fermentation. One solution is to use a lid that has been drilled to take a stopper or blow-off hose. Such modified lids can be purchased or made. You can also use the gas-in post as an outlet, which is even simpler than drilling the lid. You can replace the post with a grommet that will allow you to mount a blow-off tube or airlock. You can also remove the valve assembly from the gas-in post and fit a blow-off hose directly onto the threaded post mount.

Another desirable modification is to shorten the dip tube on the dispensing side by about an inch (25 mm). This makes it easier to leave the trub and sediment behind when transferring to a secondary or to the serving keg. This works out nicely for doing keg-to-keg transfers using CO2 rather than a siphon.

Corny kegs offer a number of advantages: they’re not too expensive, the modifications are easy and reversible, and they easily fit into a chest freezer or fridge fermentation chamber. The biggest disadvantage is the lack of headroom. Five gallons (19 l) is pretty tight; it’s best not to fill them too much past 4¼ gallons (16 l) to avoid blow-off loss.

Plastic Conical Fermentors

The next most economical choice is a plastic conical fermentor. These are usually made of HDPE plastic, so the same caveats for plastic buckets apply here: avoid brushes and scrubbies to minimize the chance of scratching the soft plastic.

The nicest feature of conical fermentors is that you can completely avoid transferring the beer. Just as in their commercial big brothers, yeast sediment and trub can be drawn off the bottom of the conical while the beer remains in place. It’s generally a good idea to pull off the sediment regularly, so it doesn’t compact and plug the drain valve. Another advantage over kegs is that conicals come in more convenient sizes that support five- (19 l) and ten-gallon (38 l) batches, or even larger. The downside is that a conical fermentor will need either a stand or a wall mount, which can make it harder to use for temperature-controlled fermentation. If you want to brew lagers, you’ll either need to purchase or build a cooling subsystem or make a custom chamber. If you go the subsystem route, you have the choice of an immersive heat exchanger and a pump or a jacketing solution. Any of these options mean more money and probably more work to get it set up.

Stainless-Steel Conical Fermentors and Brew Buckets

It would be easy to dismiss a stainless-steel conical fermentor as a needless extravagance. Sure, you could buy a room full of carboys for the price of a nicely tricked-out fermentor, but let’s put it in perspective. A top-of-the-line, 20-gallon (76 l) temperature-controlled system is nowhere near as expensive as a sports car or racing bike. With that rationalization out of the way, let’s look at your options and trade-offs.

Stainless-steel conicals have the obvious advantage over plastic, with respect to durability. The cost is significantly higher, but it’s not as big a deal when you amortize it over the lifetime of use you’ll get. Aside from the material, stainless-steel conicals have most of the same plusses and minuses. They come in a range of sizes, and you can ferment in a single container, but the size can be a bit bulky and temperature control will cost extra. Of course, there are also the intangibles. Owning one of these setups is worth serious swagger points, like driving a top-end Tesla S.

On the other hand, if you want stainless-steel but you’re still budget-conscious, you might consider some of the alternatives to conicals. Ss Brewtech has a product called the Brew Bucket, which has a conical base but simpler plumbing, and several other companies offer stainless-steel tank-style fermentors.

Take Your Pick

As you can tell, your choice will largely depend on your budget and how tempted you are by the lure of fancy equipment. Unless you decide on the corny keg option, it’s probably a good idea to scale up to a 10-gallon system or larger. The cost difference isn’t that big, and you’ll be that much closer to having your own professional-grade boutique home brewery.

From sanitation and inoculation to propagation and fermentation, Craft Beer & Brewing Magazine®’s online class Care and Feeding of Yeast has everything you need to build a healthy population of yeast and make the best beer possible.

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