Bottle Conditioning – Batch Priming

Following on from my posts on making a yeast starter, and brewing my Belgian Strong Ale, I’ve turned my attentions to my priming practices.  I have bottled all of my previous nine brews.  All nine brews have been transferred straight from my fermentation vessel (i.e. straight off the yeast cake, and into bottles primed with cane sugar.  This is where I admit to the fact that I have been adding priming sugars to each bottle individually, 1/4 tsp for 330ml bottles and 1/2 tsp for 500ml bottles.  It has worked fine for me, but I want to improve my practices and my beer.  This also means that I will be transferring all my future beers off the yeast cake (trub) before priming and racking, a practice which should further improve the quality of my beer.

This post is to document how I have calculated my priming addition and how I plan to use it, and not really a post about the relationship between yeast and sugar and practices such as re-yeasting a beer before bottling, nor is it a post on the basics of getting your beer into a bottle.

As with my yeast starter, I am using some instructions kindly provided by Dominic Driscoll from the Thornbridge Brewery.  He visited our local homebrew group back in January and talked us through the key points to consider when brewing a high gravity beer.  The instructions apply to any beer, not just those of high gravity.  I have brewed an 8% Belgian Golden Strong Ale and I want it to be carbonated in a similar way to Duvel, and I found information on this beer in Stan Hieronymus‘s book – ‘Brew Like a Monk‘.

The first step is to appreciate that there are two ways of measuring CO2:

  1. volumes (how brewers think of CO2). One volume of CO2 is equivalent to 1.96g/l.
  2. grams (how brewers calculate CO2).

Here are the components of the equation you use to calculate how much sugar to add before bottling:


A). Beer volume to be packaged (beer volume to be bottled plus any liquid you use to dissolve the priming sugars).

B). CO2 produced per gram of sugar (0.46 grams).

C). Beer CO2 prior to bottling (this is temperature dependent, see Fig. i).

D). Target CO2 level in the bottle post conditioning (typical levels for different beer styles can be found online or in homebrew books – see links below).

E). The required CO2 to produce in a bottle. The formula to calculate the required CO2 to produce in the bottle (E) is:

D – C = E

Then use your value for E to calculate the amount of sugar required:

(A * E) / B

Here is the formula in practice when applied to my beer:
D = 6 g/l (or 3 volumes)
C = 2 (taken from Fig.i)
Step 1
D – C = E
6 – 2 = 4 
A = 22 (litres of beer I want to bottle)
B = 0.46 (CO2 produced per gram of sugar)
 Step 2
(A * E) / B
(22 * 4)/0.46 = 191
So: sugar addition = 191g (sugar syrup added to beer before bottling)
…You must make correct sugar calculations, so you don’t end up with a warm room full of bombs – Stan Hieronymus’

The quote above is apt.  I emailed my calculations to Dominic to check that I had applied the maths correctly.  I had of course made a couple of errors, but the worst being my target of 4.25 volumes of CO2 (8.5g/l), based on my reading that Duvel has this amount in their bottles at the end of bottle-conditioning.  I was advised that this would end in a mess, unless I had enough Duvel bottles to use (which I don’t).  I was aware that reusing bottles, and more importantly reusing bottles not intended to be used as containers for beers with 3 volumes or above, was a recipe for disaster.  Just to be on the safe side, I have managed to source plenty of 330ml bottles intended to house Belgian beer.  My target of 3 volumes of CO2 should give me a nice fizzy beer in keeping with the style guidelines.  

Just to add, for anyone who read that last sentence as a bull would view a red flag, I am brewing a beer for me to enjoy, but also to be judged in a BJCP competition, which makes the beers carbonation as relevant as the malt bill or the noble hops I used, or the yeast (you get my point).  Brewing within style guidelines does not mean I left my creativity at the door.  Just to balance things up, my previous nine brews have all been ‘rule’ breakers….unintentionally.

If you are already brewing then you will either have your own way of priming or more likely to be using one of the many calculators within brewing software and resources on-line which will work all this out for you, but notice that most have disclaimers advising you to apply common sense where sugar additions appear to be high.  For this reason and for fun, I wanted to learn how to calculate this myself.

Other useful sources of information:

  • Brew Like a Monk (Chapter 9: Bottling).
  • TastyBrew – Bottle Priming Calculator There is a calculator, but also a useful drop-down list of ‘Average CO2 volumes listed by BJCP style’ (however BJCP do not list CO2 volumes on their site).
  • “Brew By The Numbers – Add Up What’s in Your Beer,” by Michael Hall in Zymurgy magazine, Vol. 18 No. 2, (Summer 1995): 54:61
  • Use the above, or other sources to guide you, but carbonate the beer to where you want it!
Thanks to Dominic for the information on which this post is based and to Will and anyone else at Thornbridge who advised me to the good on 3 vols.

11 thoughts on “Bottle Conditioning – Batch Priming

  1. Really interesting, I’m definitely going to try that with my next brew. Did you boil the sugar in water before adding it to the racking bucket?

    • Hi Mark. I’m yet to do this, but will be in the coming days, but all this is in preparation so that I’m good to go when the beer is ready. I understand that you make a sugar syrup using either water or some of the beer itself; boil for 5-10 mins while stirring, then cool and add to the racking bucket, giving it a gentle stir…it’s important not to splash it around or introduce too much oxygen.

  2. I generally rack off into another vessel after five days to a week, I’ve used both bog standard pressure barrels and my fermentation bucket for this secondary. If I’m using the pressure barrel, I start to let out the pressure the day before bottling, the idea being to get the beer quite flat, so it doesn’t fob into the bottles.

    I make up a DME solution, or a sugar syrup, I put this into a bucket or boiler and then decant the beer out of the secondary vessel onto the priming solution. I then bottle from this bucket, which means you don’t have to worry about trub, and the priming solution gets mixed in automagically while filling from the secondary.

    This seems to have work well for me.

  3. Really excellent post David and something I have been thinking about recently. I made some beer for my sister’s wedding three years ago and in a fluster managed to triple prime the wheat beer I had bottled. I was sure this would end in catastrophe but was saved by my very solid fuller’s bottles.

    One thing of importance I would add (particularly if you are kegging as opposed to bottling your beer), is the size of your vessel is more important than the quantity of your beer. i.e. if you were to prime 5 gallon batch (U.S. = 19L) in a regular keg (27L) but only calculate the sugar needed based on the quantity of beer, you would end up with flatter beer than you were hoping for because the CO2 you want forced into your beer will be more happy to float in the headspace (and contrast this with a 20L vessel where the CO2 would (relatively) have nowhere else to escape to because of limited headspace).

    I can send you my email correspondence on this issue I had with people in the Oxford Brewers Group if you would be interested.

    • Cheers Gregg. 2.5 volumes (5g/l) is what the chaps from Thornbridge use for Jaipur. Mine is supposed to be a fizzy strong ale, so 6g/l isn’t really enough, but I’ve been warned on going higher with the bottles I have. Thanks for reading.

  4. Interesting and thorough. At the risk of sounding like a spammer, “I’m sure gonna bookmark this for later!”

    Our worst ever brewing disaster was an attempt to brew something strong, blonde and Belgian-inspired, so we’ve yet to get the nerve up again, but we do have more than thirty Duvel bottles sitting in a box, looking very tempting…

    • Ha, you made it through the spam filter. I was really wary of getting it right for a beer that should be well carbonated, and if I compare the sugar addition calculated using Dominic’s info, to that of the online calculator I was going to use then I would have been hoping for the best. So far no explosions and still warm conditioning.

  5. Pingback: AG#11 Broadford Belgian Pale Ale « broadfordbrewer

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