Troubleshooting Pressure Fermentation: Identifying Leaks vs. Gas Absorption

Introduction

Pressure fermenting can be tricky - especially for beginners who are often grappling with some of the different concepts and potential problems along the way.

One of the questions we were asking during our first pressure fermentations was whether or not we had a gas leak, or if the gas is being absorbed back into the beer which is causing a reduction in pressure in the fermenter? 

Identifying Leaks During Fermentation

Leaks aren't so bad during the actual fermentation - you will need to have a spunding valve attached to your fermenter to help regulate the pressure in the fermenter, so a small leak elsewhere won't actually be noticed until after the fermentation has completed and pressure is no longer being built inside the fermenter by the yeast.

This is what happened to us after our first pressure fermentation - the spunding valve did it's job, and held the 10psi of pressure it was set to, and any excess was vented out via the valve as it should. Our problems began after fermentation had completed, when we saw a reduction in pressure to 0 psi overnight. We'd reconnect the gas - re-pressurise the fermenter (a FermZilla) and leave it again. We couldn't hear any gas leaks, nor could we see any bubbles forming/popping after spraying the entire lid several times with a soapy solution. Sure enough, the next day the pressure would have dropped to 0 psi again.

The Answer

We continued this process of re-pressurising the fermenter during a cold crash as well and had the same results - and we think we now have the answer to this question based on this experience.

If the pressure is dropping to 0 psi - it's a leak. Plain and simple.

If the pressure is dropping, but not to 0 psi, then it's more than likely being absorbed into the beer. 

Once we discovered the source of the problem (a carbonation cap that needed to be tightened), the fermenter would hold pressure and maybe drop a few psi overnight due to co2 being absorbed into the beer.

Conclusion

We wanted to share our experience as we could not find a definitive answer to this problem when we were facing it and er found it very overwhelming (and frustrating) trying to understand it.

A pressure gauge reading 0 can be tricky to troubleshoot

What has your experience been with gas leaks and/or  gas being absorbed into your beer? Did you find it confusing the first time as well? Leave a comment below to let me know.

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