This summer I kegged a pale ale for the first time. For about the first week or so the carbonation level on the beer was great but then the beer started to get flat (still tasted good, just no bubbles). I carbonated with priming sugar.

Once the beer started getting I did the "soap test", putting soapy water at all the connection points on the C02 canister, keg, and lines. There were no bubbles so I don't think I have a leak, this conclusion is (I think) backed up by the fact that the C02 canister is holding at a steady level.

I don't have a kegerator so the keg was kept in my garage at a temp between 65-75F. I'm using a corny keg with ball locks. Prior to kegging I replaced all the o rings on the keg.

I really enjoyed the ease of kegging and would like to continue doing it but I'd like to figure out what I did to cause my beer to go flat so I don't do it again.

What's causing my beer to go flat? A leak (how should I test for it)? Is the relatively high storage temperature to blame? I'm really at a loss and would love some insight.


Sounds like my problem is incorrect pressure for my storage temp. I'm planning to get a kegerator early next year to put this to the test.

  • 1
    what pressure did you have the gas set to?
    – mdma
    Commented Dec 12, 2013 at 0:52
  • Between 4-10 PSI. Started at 4 and tried dialing it in based on my reading about "serving" pressure. Commented Dec 12, 2013 at 4:36
  • In my experience, the opposite is true; I carb to the desired level, then connect up CO2 at serving pressure (~8psi) and over time, especially the last gallon or so, the beer tends to get foamy.
    – Wyrmwood
    Commented Dec 17, 2013 at 21:33

3 Answers 3


As you drink the beer, more CO2 needs to be put in the keg to maintain the carbonation level. For beer at 65-75F°F, that's quite warm, and you'll need around 25psi to maintain the carbonation level. My guess is that you weren't holding the keg at this pressure, so it slowly loses carbonation as the beer is consumed.

Dispensing at this pressure can be tricky - you'll need either a very long beer line (ca. 14ft) to balance the pressure, or bleed the keg prior to serving and then top up with CO2. I prefer using a long beer line, so I don't have to mess with the carbonation pressure.

EDIT: Yep, that's the problem. At 75F, 10 psi only gives about 1.3 vols of co2. 4 psi would give you less than 1 vol co2.

  • Would a kegerator completely eliminate this issue or mitigate it (is this something I need to keep mind regardless of temp)? Commented Dec 12, 2013 at 0:46
  • Yes, storing the kegs cooler will help a lot. It gets easier as you serve at cooler temps, since you require less pressure, and so shorter beer lines to balance the pressure.
    – mdma
    Commented Dec 12, 2013 at 0:51
  • If you don't mind some DIY work, you can make your own kegerator. Youtube kegerator and there's a wealth of videos on it. Depending on how fancy you go (Craig's list is your friend), you may be able to keep it under/around $500 when everything is said and done.
    – Scott
    Commented Dec 12, 2013 at 3:08
  • @Scott I'm usually all about the DIY but I think in this case I'd rather just buy a kegerator, plug it in and drink some homebrew :) Commented Dec 12, 2013 at 4:39

You didn't say what the PSI was on your regulator. It sounds like no CO2 was going into the keg or too little. What did you set your gauge at? How did the beer come out of the faucet or picnic tap? was it slow, or fast?

If it was slow, then I would say your priming sugar worked and your keg held a seal. But over time you created more headspace in the keg by drinking the beer, and the co2 pressure kept going down, and was not being replaces by the tank.

Here is what I would do. Keg the beer. hook up the gas and turn it up until it says 20 psi on your gauge. Ten pull up on the overpressure release valve on the keg cover to allow the c02 to escape. You should have heard the gas going into the keg and hear it come out with a whoosh. When you stop pulling up on the overpressure release valve, then you should hear the gas going into the keg to replace what you let out.

Then you can disconnect your tank , use the overpressure relief valve again to release pressure, and let your beer naturally carb. If you know the tank was on and co2 was going into the keg, then maybe you had your pressure too low. Perhaps 30 is needed to keep your keg carbed, but when you want to serve it, reduce the pressure by lowing your gauge to 10 and letting excess co2 out of the tank.

There are mistakes to make when kegging, don't give up.

  • So keep it at high pressure unless serving. When serving bleed off the C02 in the headspace with the release valve, then reduce pressure. After serving bump the pressure back up. Sound about right? Commented Dec 12, 2013 at 0:43
  • 1
    Be warned, in my experience, excessive bleeding of the pressure in the keg will kill your aroma, which is not a desirable trait in almost every beer style, especially hoppy beers.
    – Scott
    Commented Dec 12, 2013 at 3:05

9 times out of 10 you have a leak. If you have ball lock corny kegs like I do- check the O rings on the connects. The keg could be holding pressure fine, but leaking when you hook it up.

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