Bubble Bobble

Within 48 hours of starting fermentation, the airlock at the top of your fermentation vessel should start bubbling as the yeast produce CO2. Here’s the carboy containing our India Pale Ale, 24 hrs after starting fermentation.

You can see small bubbles in the airlock at the top of the carboy, and if this picture were moving, you’d see the small plastic insert inside the airlock bubbling a few times a minute.  However, you can also see the croizen (foam) at the top of the beer within the carboy getting dangerously close to the top of the vessel.  Obviously, this presents a dilemma.

There is little space at the top of the carboy for CO2 to collect, and it is also difficult to escape, as you are trying to limit exposure of the beer to the outside world for fear of contamination by various critters in your cellar-like basement.  Keeping it mostly sealed yields the possibility that you are forming a “beer bomb” that could explode due to the increasing pressure within the sealed vessel.

Therefore, taking my boss’ advice (who’s had this problem in the past), we did the following:

This picture is of the Hefeweizen, a beer that was already filled too high because I overfilled it with water.  Since taking this picture, I’ve also set up the IPA carboy to do the same thing.

Basically, we kept the rubber stopper in the top of the carboy, but rather than use the airlock, we took silicone tubing that came with the beer kit to allow the foam and air to escape into another vessel.  You can see the foam inside the tube, and collecting in the Mason jar Brooke set up to catch the croizen that is escaping from the carboy.

While not ideal, it should help limit contamination as long as we don’t leave it like this permanently.  With the near constant flow of croizen through the tube, bacteria/insects/mice probably won’t be going backwards toward the beer.  Also, the brunt of the croizen production occurs within the first few days, so I’ll be able to remove the tubing and replace it with the original airlock again shortly.

We didn’t have this problem when we were using the 5 gal plastic bucket because there was plenty of space at the top for air to expand into.  Also, the design of the airlock we were using may have been a bit better suited for allowing at least some of the CO2 to escape.  And finally, any time I would open that thing up, all that excess CO2 could escape rapidly, rather than trying to fit all of it through a relatively small opening at the top of a carboy.

Regardless, it’s interesting to see the process in action through glass.  I may only use glass carboys for the secondary fermentation process in the future, to help prevent this kind of thing from occurring, but I’m still glad we did it this way.