Now that brew day is complete, and your wort has been fermenting, and has turned into beer. You’ve been watching your airlock, and it has slowed down to a very intermittent and less vigorous bubbling. Once the airlock has finished bubbling completely, wait 24 more hours, and at this point, you are now ready to transfer your beer to your carboy for the secondary fermentation stage. This is the fastest and simplest phase of the brewing process, so you don’t need to set aside much time to get this done. The process for transferring the beer for secondary fermentation is largely identical to transferring the wort into the primary fermenter, but there are a few key points to note. As with all steps of the beer making process, we start by ensuring that all of our equipment is thoroughly sanitized, so once again, you want to gather your equipment and go through the same process that was used on brew day. The equipment needed is not as vast for the transfer, so this process of sanitizing will take less time than it did on brew day. Most people use a carboy for their secondary fermentation stage, and this is the norm that comes with most homebrew equipment kits. We’ll assume you’re using a carboy for your secondary, and as such, the items you will need to sterilize/sanitize for this process are as follows: carboy, auto-siphon, tubing, carboy stopper/bung, airlock, and hydrometer.
You may be wondering why you would go through the trouble of moving the beer from one container to another, and why you can’t just leave it to complete the fermentation in the primary fermenter. The short answer is that you can do that, but there are multiple benefits to transferring the beer to a separate container to finish the fermentation and 2 week rest period (higher ABV beers benefit from a longer rest period in secondary). What is actually happening during the transfer is that you are moving the beer off of the settled sediment (bits of grain, hops, and dead yeast/the yeast cake) which can produce undesired or off flavors in your beer. The secondary fermentation also allows more time for your beer to continue letting fine particulates settle to the bottom of the carboy, which will in-turn present a cleaner, clearer finished beer. Secondary fermentation is not required, but it does enhance the final finished product. Most brew-in-a-box kits will recommend this, and while it isn’t technically necessary (especially for a lower-gravity, lower-ABV beer), it is a process that is worth the relatively minimal effort involved to accomplish. Utilizing the secondary fermentation phase is also good practice for when you do eventually brew a higher gravity beer that will greatly benefit from the practice.
Before you start the transfer, take a gravity reading of the beer to have an idea of where your beer is currently sitting. If it deviates greatly from your target, this is the time to make corrections before you transfer to your secondary. This process is the same as the gravity reading we took of the wort before transferring to the primary fermenter. Again, I recommend writing this down somewhere in your beer log so you don’t lose it. At this stage, you can calculate the ABV of your beer with a simple formula. The formula is (OG – FG) X 131.25. That is the original gravity (the first reading you took from your wort before the fermentation started) – (minus) the final gravity (the reading you just took of your beer) X (multiplied by) 131.25. The resulting number is the ABV of your beer. This can continue to fluctuate during the secondary fermentation, so you’ll want to make sure to write down your gravity readings somewhere you can easily reference. If you find your ABV is below your target, you can add additional sugars to your beer before you transfer to the secondary, but as with all things related to that beer, you need to make sure to sanitize anything that will touch any aspect of your beer, so make sure to sanitize the pot you use to mix the water & sugars. If you need to add sugars, you’ll want to dissolve them in clean (bottled) water, and add that solution to your beer. You can use additional malt extract (if you bought extra beyond what was needed for your beer recipe), or any sugar source (white granulated sugar, brown sugar, candy sugar, honey, corn syrup, etc). Just as with malts, the sugar source will have a flavor and color impact on your beer. Darker sugars and malt extracts will produce both more color and flavor than using granulated table sugar, and are more suited to darker beers and vice-versa. 1 cup of most sugar sources dissolved into your clean water solution will add 1% ABV (on average) to the beer for a 5 gallon batch.
Once your equipment is sanitized, and you’ve made any sugar additions (if you’re using a pre-made kit, this shouldn’t be necessary) you’re ready to start the transfer. I recommend a height separation between your primary fermenter and the empty secondary. If you have a carboy harness, now is the time to fasten your carboy into it, as it makes moving around a heavy beer-laden carboy much simpler. Put the primary above the secondary (on a table, sturdy chair, etc.) and your secondary on the floor (if it’s a glass carboy, place a towel on the floor before you set the carboy down). If the primary is above the secondary, it will help the flow of the beer between the containers – gravity is your friend. Just as with the wort transfer, you’ll connect your tubing to your auto-siphon, and will put the auto-siphon into the beer in your primary fermenter, and the end of the tube into the carboy (or whatever your secondary vessel may be). One important note is that oxygen is not a friend to your beer, so you want to avoid splashing the beer during the transfer, so make sure to get your tube in your carboy down into the vessel as close to the bottom as you can. Additionally, just as with the wort transfer, there will be trub (grain, hop, and yeast particulates) that settles on the bottom of the primary fermenter, so don’t put the auto-siphon all the way to the bottom of your fermenter. Just as with the wort transfer process, you’ll be able to see the trub line as it gets closer to the bottom, and again, I recommend stopping before you get to that line so as to avoid transferring any unwanted sediment.
Once the beer is transferred to the carboy, you’re ready for the secondary fermentation phase, but it is at this stage, before we put in the stopper and airlock, that we will add any desired additional flavor/aroma ingredients. If you’re dry-hopping an IPA, adding additional hops to the beer in the carboy at this stage will draw out aroma characteristics (and some flavor as well) but won’t extract additional bitterness into the beer. If you’re making a flavored stout with vanilla or cinnamon, or whatever ingredients you choose, this is also where you would add those ingredients. The only real limit is your imagination, so feel free to experiment. If you’re using a ready-made kit, they would have everything you need included, and most won’t be adding ingredients at this point. Most ingredients will float on the top of the beer, and you don’t need to worry about them being soaked or stirred in at this stage. Indeed you want to avoid any undue agitation, as agitation creates exposure to oxygen, which we want to avoid. Once all of your ingredients are added, put the stopper in the carboy, and the airlock in the stopper (filled with clean, bottled water yet again). It is advisable to fill the airlock with water before you put it in the stopper, as if you overfill, you don’t want that water to drip into your beer. A tip for the stopper is to make sure that the neck of the carboy as well as the stopper itself are dry, as the stopper is smaller than the carboy neck opening, and if it’s wet, it will often want to try to back out of the hole. As with the primary fermentation, you want to move your carboy to a cool, dark place to rest. The secondary takes a bit longer than primary fermentation, and it is advised to let it sit for 2 weeks (minimum). That’s all there is to it. Once more, we’re just waiting on time to take its course, so sit back, grab a beer from the fridge, and pat yourself on the back for a job well done.
The Craft Beer Corner 