You know what they say about ASSume

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You know what they say about ASSume

Post by JR. » Mon Apr 09, 2018 4:02 pm

I recently got tangled up in multiple incorrect assumptions trying to troubleshoot a problem.

I changed to a new design beer fermenter that I really like (Fermonster).. The smooth plastic (P.E.T.) vessel is easy to clean and clear so easy to see the beer fermenting inside.

BUT, there has to be a "but" or why write about this? I wasn't getting good bubbler action. When fermenting beer the yeast microbes eat dextrins (sugars) and expire CO2, which will build up pressure inside an unvented fermentor. The bubbler is a simple air lock that allows CO2 to escape but not allow room air back in, to prevent contamination. Over decades of home brewing I am familiar with a pattern of initial pressure build up and slow tapering off as the yeast run out of sugar to consume. I was not getting a proper gas tight seal so no reliable bubbler action.

The Fermonster uses an o-ring seal in the screw on lid and that was the obvious suspect. When I contacted the manufacturers customer service I was advised to watch two videos describing how to properly install the o-ring... I watched the video before filling out the contact form, and believe it or not, I already knew how to install o-rings. The customer service guy (nice enough) kept insisting that I view the videos again and that the o-ring is harder to install than it seems.

I was suspicious of the o-ring seal integrity and macgyvered a DIY gasket from some dense foam sheet I had laying around to put on top of the o-ring. It seemed to help but after a few days the bubbler action was still not 100% (decayed too quickly).

Being accustomed to encountering incompetence I decided to second guess the o-ring size. After way too much time making difficult measurements with an old swedish vernier caliper (that may be older than I am), I determined that the only standard value o-ring sold that fits, is what we had.

Another data point, the fermenter maker sells a lid wrench for unscrewing tight lids. The customer service guy suggested that the lids get tight from the pressure built up during a fermentation.... cough, not even close. :lol: With a bubbler the internal pressure is vented, so close enough to atmospheric pressure to be considered the same. Lids get tight for other reasons. :lol:

I bought a wrench for tightening, as my arthritic fingers are not as happy as they were when I was younger tightening stuff :roll: .

Long story much shorter... I finally figured out that the problem was the hole in the rubber stopper was too loose around my bubbler tube, causing the gas leak. After I corrected that seal, the bubblers started bubbling properly. :D

I incorrectly ASSumed that the o-ring was the problem. The customer service guy ASSumed I was on the right track asking me to watch lame "how to install an o-ring" videos over and over.

Two ASSumptions did not cancel but actually reinforced.

Customers (like me) can be wrong in any number of ways.

Don't only half-ass tune your drums. Visit to hear what properly "cleared" drums sound like.

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