inconsistent Bottle Carbonation

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Active Member
Jan 26, 2022
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I have been getting inconsistent carbonation since I started back brewing earlier this year.

One batch of a light ale I made for my wife recently....US05 yeast fermented well, but hardly any of the bottles are carbonated to target.
Most are not completely flat, but not carbonated to any acceptable level.
This beer was bottled on 8/22/22 and we had 2 last night 10/30/22 that were relatively flat.
After bottling it was kept in a storage section of our garage which temps have been 67-72 degF during that time.

My typical process is ferment 6 gallon batches in a 6.5 gallon Big Mouthed Bubbler for 2 - 3 weeks at 68-70 degF.
On bottling day::
Use beersmith to determine the sugar (sucrose) addition required for a target carbonation level.
Weigh sugar and mix with 500 - 750 mL of water and heat to 180 - 190 degF to dissolve and sanitize a bit.
Cool a little.
Begin the transfer process from the Big Mouth Bubbler to a bottling bucket.
Once a small volume of beer is in the bucket add about half of the sugar water and stir with sanitized spoon.
When about half of the beer has transferred to the bottling bucket add the remaining sugar water and stir.
Stir again at about 3/4 transfer.
Stir at the end of the transfer.

I use a mixture of bottles, but am most heavily invested in the Kegland PET bottles with the screw on caps.
They are new.

Just wondering if anyone sees anything obvious here I might be missing.
It could just be the cooler temps but when I read that people are drinking their beers after bottling in 2-3 weeks, I can't help but wonder if I'm missing something.


Well-Known Member
Oct 24, 2022
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Out Riding
Those PET bottles normally become very firm, if not solid, from the carbonation. How firm are the PET bottles when you drink them? If they are even a little bit soft it may indicate the need for warmer temperatures, more priming sugar and/or more time for full carbonation.

Calculating priming sugar per bottle volume and dosing per bottle may be more accurate.

When using the Mr. Beer PET bottles (750ml) I use a minimum of 2 teaspoons (5 grams per teaspoon) of dextrose per bottle.