first time natural carb in keg

Decided to give my big RIS a chance to naturally carb since it needed another month of aging so I pitched 4.5 oz of bottling sugar in a 5 gallon corny... Every few days id do a quick pull on the relief valve hoping to see if any pressure was building up but I didn't get any for about a week. I picked up a pressure gauge and relief valve setup. When I added it, it showed no pressure.

I figured maybe I had a leak so I hit the keg with 5 psi from my co2 tank seeing if that would seal it. Well, that revealed that I had a leak on the gas in tube as I could hear the leak. Replaced the oring a lubed it up. Re pressurized to 10 psi and over the next few days the pressure dropped.

What I'm wondering is whether all the natural co2 is already gone, or should I repitch? I was thinking that the drop in pressure is the beer absorbing the co2 but since I had a leak... When should I expect a rise? Oh I've got the keg inside the house at about 76F.

Thoughts?

I am no expert, but if pressure never built in the keg, you probably do not have carbonated beer. You lost whatever CO2 that was formed in that week off of the priming sugar. There may or may not be fermentable sugar left in the beer so I wouldn't reccomend re-priming with a full amount of priming sugar for fear of overcarbing. Additionally I have read that you use less priming sugar in a keg than you would in individual bottles for fear of overcarbing. Is it possible to set/forget or force carb the keg? Those are probably your best bet, or you coulc put enough pressure into it to seal and let it condition and then test/carb up once it finishes its term in solitary.

Just my $0.02

If you had a leak in your keg, you likely got very little CO2 to dissolve in your beer as your priming sugar fermented out beyond what was already there from primary fermentation. You need to have a sealed keg or bottle to get your beer to carbonate properly. If the package isn't completely sealed, and doesn't hold pressure indefinitely, your beer will lose carbonation over time.

Until you have your keg to the point where it does not lose pressure, adding more priming sugar won't do you any good. The additional priming sugar will ferment, but the CO2 will eventually make it's way out of the leak and you beer will end up flat.

I'm still a little concerned about the pressure drop you've seen after hitting the keg with 10 psi. Has it dropped and stabilized or has it continued to drop? If your initial priming sugar has already completely fermented, which is likely, you should not expect to see a pressure increase until you add more fermentable material.

I'm thinking your best bet here is going to be just to force carbonate once it has aged rather than trying to figure out how much more priming sugar to add.

The Homebrew Nerd
thehomebrewnerd.com

TheHomebrewNerd said:

I'm still a little concerned about the pressure drop you've seen after hitting the keg with 10 psi. Has it dropped and stabilized or has it continued to drop? If your initial priming sugar has already completely fermented, which is likely, you should not expect to see a pressure increase until you add more fermentable material.

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It has continued to drop, I haven't poured a sample to see if the beer is accepting co2. Recall that when force carbing, we're applying *continuous* co2 and the beer absorbs it over time. So my thought here is that (1) I don't have any sugar left, the co2 generated there went out the leak (2) I believe the leak is closed as I cannot see or hear any leakage via testing methods; note I haven't submerged it... (3) I'm attributing the co2 loss now to beer absorbing the co2 that I injected.

The only real way to tell if the keg stays sealed would be to jump the beer into another known good keg and pressure test the current keg the beers in.

So, in the end, I think you're quite right. Best bet for now is to just force carb and take this as a lesson learned about pressure testing the keg prior to trying to natural carb in it.

ne0t0ky0 said:

It has continued to drop, I haven't poured a sample to see if the beer is accepting co2. Recall that when force carbing, we're applying *continuous* co2 and the beer absorbs it over time. So my thought here is that (1) I don't have any sugar left, the co2 generated there went out the leak (2) I believe the leak is closed as I cannot see or hear any leakage via testing methods; note I haven't submerged it... (3) I'm attributing the co2 loss now to beer absorbing the co2 that I injected.

Click to expand...

I understand what you are saying on your point (3). I guess I'd have to pull out and old chemistry textbook to remember how exactly CO2 dissolving in liquid works, but I guess it makes some sense that you would see a drop in pressure as some of the CO2 initially in the headspace begins to dissolve into the liquid. At some point though I would expect an equilibrium to be reached and the pressure drop should cease before it drops to zero. If equilibrium doesn't happen it could be a sign that you still have a leak.

Since you continue to see a pressure drop, I'd probably just recharge the keg periodically by reconnecting the gas to keep the pressure close to the level you need for your target carbonation level.

Anyway, good luck. Hope you are able to get it all figured out!

The Homebrew Nerd
thehomebrewnerd.com

First of all...Big RIS...will probably take 1-3 months to carb up with priming sugar depending on yeast vitality. If you pitched fresh yeast, probably on the lower end. If they were stressed out in high ABV, towards the longer end.

Second if you have beer thats barely carbonated, the 10 psi that was given to pressurize the headspace will simply absorb into the beer. It will do very little to actually carbonate the beer though if you disconnect it. Equilibrium will not be reached at room temp with this charge and disconnect method. At least not for a long time.

Thirdly, its always a good idea to purge headspace and then hit the seals with 30 psi to properly set them after addding priming sugar. The 30 psi will not make a dent on the eventual carbonation, it will just ensure your lid is properly sealed to keep your priming CO2 inside the keg.

Unless you have this big bad boy on a time clock, I'd simply stash it away at room temp for a couple of months. After you've given enough time for the yeast to consume all of the priming sugar, cool it down for a few days and then take a sample. If its not carbonated to your liking, force carb it with usual methods.

I'd pitch more sugar, hit the keg with 30 psi, and leave it alone! The pressure will go down again as the CO2 is absorbed, but should start going back up in an couple days.

After reading the replies from solbes and david_42, I got curious and did some reading on the solubility of gasses in liquids to refresh my memory. In my original reply, I was definitely underestimating how much CO2 5 gallons of beer could hold at room temperature.

I won't bore you with my calculations unless someone is really curious, but it does seem that 5 gallons will hold much more CO2 than you will add by initially filling the keg headspace at 30 psi.

So, in the end I am agreeing with the others. If you initially charge with 30 psi and a dose of priming sugar, you will see a significant drop in pressure as the initial CO2 dissolves into the beer, and the pressure should again start to increase once the yeast start fermenting the priming sugar. If you didn't add any priming sugar, the equilibrium pressure would be pretty low from the initial 30 psi charge...much lower than I was initially guessing based on my gut instinct.

Guess I should have done the calculations first! Always something new to learn in this great hobby.

The Homebrew Nerd
thehomebrewnerd.com

Awesome advice! I've hit the keg with 30 psi. Gonna leave the pressure tester off for a week and see where it's at. In about two weeks ill chill it down and see what the carb level is like. I'm gonna jump half the keg for serving and age the second half. I can see about pitching some more sugar for the part I'm gonna age.

Thanks for the tips on natural carbing. I'll let you know how it turns out.