I've had a little trouble with carbonation after bottle conditioning lately. A few consecutive batches actually. I have started replacing items such as my bottling bucket, hoses and the like. I'm down to my glass carboys as a suspect. I sanitize them with Star San and let them dry, I don't rinse them as per the intsructions.

A rep with 5 Star came to one of our homebrew club meetings and explained that letting the Star San dry will form an active anti-bacterial barrier that will for a while provide protection against contamination while the carboy is empty. I seal the carboy with a cap for the week that it is not in use, however, I have not been rinsing it before transferring my delicious beer into it. I'm wondering if the "still active" Star San is hindering my yeast and that is why my beer is not fully carbonating. Any thoughts? Any experience? Should I look at something else as the culprit?

I have since started rinsing out my carboys so I will know pretty soon if this fixes my problem but I'm just curious if any of you have any thoughts.

  • Are the bottles carbonated at all? Commented Oct 28, 2010 at 17:23
  • Yeah, they're just between flat and normal. I've double checked how much sugar I'm using but they're probably only at 1 carbonation volume.
    – dzachareas
    Commented Oct 28, 2010 at 18:56
  • Tell us more about your primary fermentation practices, length temp etc etc. Are you using White labs yeasts, dry yeasts??? I doubt you are picking up too much starsan in the bucket too. What temp are you keeping the bottles at. Make sure they are a good 70F for two weeks or more to be fair in judging carbonation.
    – brewchez
    Commented Oct 29, 2010 at 15:35
  • I have an extremely hard getting back on to this site for the last couple of weeks and have had to start a new profile in order to get in to post something. I ferment for one week in the primary and one week in the secondary, I bottle and keep everything at about 71 degrees. Even after a month, 3 out of my last 5 batches have been under carbonated, significantly, the 2 batches that did carbonate took about 6 six weeks to finally carbonate. I have used both White Labs and Wyeast yeast and haven't noticed a difference between the two.
    – dzachareas
    Commented Nov 22, 2010 at 14:45
  • I'm wondering if I'm not being gentle enough when transferring to my bottling bucket and I'm releasing some of the CO2 disolved in the liquid so I'm starting with less CO2 when I bottle. I don't know, just a thought. I do try to be careful though.
    – dzachareas
    Commented Nov 22, 2010 at 14:47

3 Answers 3


An infection is not a likely culprit for undercarbonation. Nor is the StarSan, provided that you let the bottles dry completely. I always give stuff a quick rinse after using sanitizer because it always seems like I don't have enough time to let things dry out completely. I feel better with a quick rinse--I don't want whatever chemical is creating that "active anti-bacterial barrier" in my beer, however little of it there is.

Undercarbonation is most likely caused by not using enough priming sugar and/or having yeast that is too tired to finish the job--which often happens with higher gravity brews. I recommend using a priming sugar calculator like this one: http://www.tastybrew.com/calculators/priming.html , and cultivating healthy yeast by using yeast nutrient during the boil and adding pure O2 using an oxygenator before pitching the yeast.

  • Star San is explicitly no-rinse, and surfaces do no need to dry. Not that most municipal tap water is much of an infection rinse, but why bother sanitizing if you're just going to re-"contaminate" the surface with water?
    – jsled
    Commented Nov 26, 2010 at 17:36
  • I've rinsed with pre-boiled water after cleaning with Star San. My beers have turned out nicely and well-carbonated too. Commented Dec 13, 2010 at 23:50
  • While it's totally fine to rinse after star sanning (their site has both rinse and no rinse directions depending on application) I've lived in areas where the mineral content of tap water is high enough that I wouldn't want that residue in my bottles, even if sanitary. Star San also has the benefit of reducing mineral build up on the glass.
    – chrisst
    Commented Jan 25, 2013 at 17:12

No, the StarSan will not significantly hinder carbonation. A week is a bit long. I generally rise and pour the beer in right into the still-wet bucket. It's not a problem. I don't think letting the starsan dry is actually a best practice but it still isn't your issue unless you are getting infections. In short, StarSan isn't your issue.

Could you elaborate what your trouble is? No carbonation? Infections? Low carbonation? Could help more if I knew more. Beers that secondary for a long time or have a particularly flocculant yeast sometimes need a bit of a boost.

  • It's low carbonation, and some bottles are a little more carbonated than others. It's happened consitently on my last four batches, all of which were different yeasts. I've changed out my racking cane (auto-siphon), bottling bucket and hoses for fear that I picked up an infection, although I never saw any sign of it. They each sat in the secondary for 1 week. I appreciate your help.
    – dzachareas
    Commented Oct 28, 2010 at 19:39
  • 1
    If you have uneven carbonation between different bottles from the same batch you may have had uneven levels of priming sugar in the bottling bucket. Might help to stir up the batch after adding the priming sugar to make sure it is distributed evenly.
    – markskar
    Commented Nov 9, 2010 at 18:00

Always use star san right before bottling,never ever had problems with this product. Dont fear the foam!!!!

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.