I’m not exactly sure why homebrewers settled on 5-gallon (19 l) batches; it may be related to soda keg sizes and manageable carboy volumes. Like most brewers, I just fell into line and never thought much about it until I started looking into improving my brewing setup. Stepping up to a 10-gallon (38 l) system barely changed the price over a new 5-gallon (19 l) setup, so it was a no-brainer. Of course, once you have twice the capacity, you might as well take advantage of it.
It turns out that the work differential is a lot like the initial cost of the equipment. For about 1.25 the effort, you can end up with twice the beer. Heating the hot liquor or getting a boil underway takes a bit longer, but that just gives you time to sip a little more beer while you wait. Of course, I did have to adjust my recipes to the new setup, but soon enough, my house beers tasted exactly how I wanted them.
Vive la Différence
My beer was good, but there was one surprise with split batches. While the beer seemed consistent enough from batch to batch, the two halves of a 10-gallon (38 l) batch could be noticeably different. It wasn’t a radical divergence, but the gravities might not be quite the same or the hops character could be slightly more pronounced. Side by side tasting revealed how inexact a science this is at the homebrew scale. There are just too many variables: one carboy might be a touch warmer, the yeast pitch rate is never quite the same, or the oxygen saturation might vary.
For quite a while, I celebrated the individuality of each half batch. It was fun to see where each would end up. Eventually, though, I decided to see if I could adapt my process to flatten out the variance.
Blending for Consistency
I was already making a reasonable effort to manage my brewing. I measured out my yeast starter across the two batches, I made sure the starting gravity was the same, and I had a temperature-controlled fermentation chamber. Since I was still noticing differences in flavor, blending seemed like the best technique to fix it. Combining the two batches erased the variation.
Rather than waiting until bottling or kegging, I decided to mix the beers throughout the brewing process so they’d stay as synchronized as possible. That may be unnecessarily extreme, but I’ve been very satisfied with the results.
From the Kettle to the Carboy
I usually whirlpool my wort before chilling it down, which should take care of any stratification in the kettle, but I still opted for a mix at this stage. It’s probably not necessary, but the last of the wort definitely gets a little more time in contact with the hops that I leave behind, so it seems worthwhile. I fill the first carboy about halfway, then switch to the second, filling it completely. Then I switch back to the first carboy to finish it off.
Rack ’em Up
Each time I rack, I do a similar mix. Starting with the first carboy, I transfer half the beer into one new carboy and put the rest in a second new carboy. Then I do the same thing with the other full carboy, splitting it across the two new vessels. I also check each one along the way to measure the gravity and taste the differences. I’ve never had an infection issue crop up, but I wouldn’t want to ruin both halves if one was bad.
Final Mixdown
Finally, I follow the same blending process when the beer is ready for kegging, making sure each keg is a blend of the two carboys. I also use a tee-split CO2 gas line to make sure the pressure is consistent.
It’s a little more complex if you bottle, unless you have a 10-gallon (38 l) bottling bucket. For the rest of us, it’s best to rack half of each carboy into the bottling bucket. After that’s bottled, you can repeat the process with the second half of each carboy.
Merge Overkill
Is all of this necessary? Probably not, but now I don’t have favorites between the two halves of a batch. Also, I don’t do it for every 10-gallon (38 l) batch. Sometimes, I take advantage of the split to experiment, treating the two parts differently. It’s a great way to compare yeast strains or diverge in the secondary with dry hopping or adding spices or fruit.
The larger batch size also makes it possible to do collaborative brewing, where I connect with another brewer, but we’ll each get a full batch of beer. These are just some of the advantages to scaling up your equipment.