How often is too often for checking ABV?

ChicagoJim · Sep 19, 2014

Hi All,

New brewer here. I'm on my second batch and am still fumbling my way through absorbing volumes of information from this and other sites.

I would assume the jitters about contamination will settle after a few successes under my belt, but right now I think I have a healthy "Respect" for what can go wrong.

My current brew recipe, a Simcoe IPA, is telling me to check the ABV in my primary fermenter for 3-4 days in a row to ensure fermenting is done. My question is, how to I continuously crack the lid on my plastic bucket fermenter to check this without dispersing the CO2 and avoid O2 and contamination? I plan on not doing secondary fermentation on this batch, but would like to know the ABV. Is it a big deal to thief some brew and test as long as I reseal immediately after taking the sample and don't return the tested portion?

Thanks in advance for the advice!

sbaclimber · Sep 19, 2014

Very good question.
Although what I do may totally conflict with recommendations and what others do, I'll share anyway...
I have never taken a reading prior to bottling....for better or worse.
Up until now, I have only used 2 different ale yeasts, WLP007 and US-05.
What seems to work for both is to wait for airlock activity to drop to almost a stop (<1 bubble/min) at the preferred fermentation temp (e.g. US-05 = 15°C) and then bump the temp up to the max recommended for the yeast (e.g. US-05 = 22°C) for 3-5 days, then bottle.
Measured SG at the time of bottling is within a few fractions of a degree of the FG after bottle conditioning.
Did it take a while to figure out how this system works for me? ...yes
Did I end up with many batches of over-carbonated bottles before I figured out the system? ...yes
Would I recommend my system? ....depends on how much trial-and-error you are willing to go through.

PS, the critical point is making sure fermentation has stopped before bottling.
Neither airlock activity nor manufacturer's predicted attenuation for a particular yeast are particularly good indicators. Either you measure, measure, measure, or you (like me) run through a few similar batches to get a feel for your system.

Ozarks Mountain Brewery · Sep 19, 2014

everyone does it different for each type of beer but the general waiting period for fermentation is 7 to 10 days depending on the yeast I might add but after that you first check for positive pressure, watch the airlock, push the lid down is it gushing of faint , faint is better, then pop the lid after the 7 to 10 days , check the ending gravity with your recipe, don't worry about checking it again if it's reached it say 1.012. if its not close put the lid back on and check again in a couple of days