Et Tu Airlock? By: Ben Bakelaar

Has your airlock ever betrayed you? I know mine has. Those @#$% things pop out, shoot out, slide out, foam over, you name it. You get a dropping sensation in the pit of your stomach, and wonder, is my beer ruined? Well, honestly, you never know. Don’t jump to any assumptions – my recommendation is to cap it back up and wait out the fermentation  [Editor’s Note:  Be sure to re-sanitize!]  . If you don’t get any off flavors post-fermentation, you’re good! And if you are a paranoid sanitizer like me: you might be surprised that a little (or even a lot) of air exposure or crud exposure (of the hop foam kind) doesn’t necessarily immediately ruin your beer. Try to swallow your OCD tendencies which immediately shout “Bahhhh! It’s ruined!! Dump it!!!” and practice the ancient art of patience.

In order to avoid these sorts of airlock mishaps, I am going to review every single type of airlock I’ve seen, tried, or heard about. Not all airlocks are created equal, and some types will be better suited for certain containers, fermentation temperatures, yeast pitching rates, etc.

Before we dive in, though, let’s re-introduce the one thing that makes most airlocks possible: the bung.

Carboy Bung  |  love2brew.com
First, we have the All-American Classic ©, the three-piece airlock. At $0.99 a pop from Love2Brew, don’t buy one when you can buy three! You never know when you might want a fresh one. Make sure to fill up the airlock about 1/3 to ½ with a liquid barrier, whether that’s distilled water, vodka, StarSan (diluted, not raw). Don’t forget your bung.

Three Piece Airlock  |  love2brew.com
Next up, what I like to call the Euro Special, the bubble air lock. This thing just screams old school at you, like it came out of some 1940’s Looney Tunes laboratory. I have no experience with these at all, but they work pretty much the same as the three-piece. Sure at $1.19 it’s 20 cents more than a three-piece, but just think about how much more impressed your friends will be. Grab a few, why don’t ya? Don’t forget your bung.

Bubble Air Lock  |  love2brew.com
Now let’s advance to the next level of brewing, where we get into “blowoff” tubes. Simply put, if your fermentation is going to be vigorous, or has limited headspace (remember you should ideally have 20% of your carboy empty, i.e. 6.5 gallon carboy for 5 gallons of liquid, or 5 gallon carboy for 4 gallons of liquid), a simple airlock may not be enough. Airlocks restrict the flow of gases between the carboy and the outside world – that’s their job. But that restriction has the effect of building up pressure inside the carboy, and that’s where most homebrewers hit their first airlock mishap. A blowoff tube simply allows the gases to escape the carboy more efficiently. There are several ways you can hook them up. Just don’t forget that the other end has to go in something. I tend to use a growler filled about 1/5 with regular tap water and a little sanitizer (those germs *cannot* go UP the tube).

Growlers  |  love2brew.comSiphon Tubing  |  love2brew.com

First, and this is the simplest/easiest method I’ve ever seen which Ron introduced me to: jam a tube in the bung! Because tubing is flexible, it really doesn’t matter what the internal diameter is. Grab 3-6 feet of siphon hose, heat it up under some hot water if necessary, and stick it through the drilled hole in the bung. You might have trouble with ½” hose, but definitely not with 3/8 or 5/16.

Siphon Tubing  |  love2brew.com
Second, if you want to be more careful about it, you can stick the siphon hose on to the inner part of a three-piece airlock. Just leave the cap and the internal piece off. For this, you will probably want ½” hose. And here’s a tip: if you are using temperature control in a limited space, you might find that your carboy + airlock + siphon hose is too tall and hits the top of your fridge/box. In this case, you can saw off most of the airlock, just leaving enough of the base (which goes into the bung) and the extension to affix the siphon hose on to.

Three Piece Airlock  |  love2brew.comSiphon Tubing  |  love2brew.com

Third, and lately I’ve found this one the easiest, is using a carboy cap. Sure they cost a bit more, but they are super convenient and hold on to the outside of the carboy, as opposed to the bung which sticks to the inside. Hook up some siphon hose to either of the white caps (you only need one blowoff tube), and you are all set! Remember that in this scenario, you don’t need a bung or a plastic airlock. And even if your fermentation is going to be slow and normal, this still works! I am a big fan of *not* artificially building up pressure in the carboy – just let the gas get outta there!

Carboy Cap  |  love2brew.comSiphon Tubing  |  love2brew.com
Now, speaking of that, I am going to introduce you to some “hack” airlocks which I swear to you do work, especially in a pinch but even as a regular solution.

First, there is cheesecloth. From what I’ve heard, old school homebrewers (i.e. pre-1990s) would simply cover their fermenter (probably a 5 gallon plastic bucket) with a piece of cheesecloth and then use a rubber band or some string to tie it on. Remember all you need to do is allow CO2 to escape, and nothing outside to get in. Cheesecloth will certainly keep debris out, and as far as gases go, once CO2 is produced, it does form a blanket inside the bucket, so I doubt any oxygen is sneaking in through the cloth.

Cheesecloth  |  love2brew.com
Next, and this one I might catch some slack for… saran wrap (or aluminum foil in a super pinch)! I have personally done this several times with no ill effect on my beer. You just wrap the saran wrap over the top of the carboy (glass in my case), and then use a paperclip or better yet a pin to poke a few holes. That will allow the CO2 gas out at a natural rate, i.e. no building up of pressure. Those tiny pin holes are likely not going to allow anything bad in. Do I recommend this as a first course of action? No, but it can and does work, so you can decide what scenario might be appropriate. I’ll tell you one thing, it was a lot quieter in the house without a blowoff tube or airlock bubbling. J

Plastic Wrap  |  love2brew.com
This brings us almost to the end, but believe it or not there are still 2 more options!

A foam stopper is typically used in yeast starters with an Ehrlenmeyer flask, but there have been many times when I ended up dropping one of these bad boys into my glass carboy for one reason or another. Note, they *will* pop out under CO2 pressure. One suggestion would be to use these for secondary, so you can utilize your airlock (but you already bought more than one, right?) for a new batch.

Foam Stopper  |  love2brew.com
And finally, the mother of all airlocks, the latest and greatest that science has to offer us, the dry airlock! To utilize this, you are going to have to pick yourself up a Better Bottle from Love2Brew. Grab a ported closure, and then a dry trap. Please note, as on the product page, “love2brew does not recommend using these for any vigorous fermentations; instead start with a blow off tube and switch to the trap after transferring.

Ported Closure  |  love2brew.com