recent brews have finished around 1.020 - any ideas as to why?

I have had an issue with most of my recent brews getting stuck around 1.020 when finished. I have created a table below to list OG, FG, Yeast, and Time Fermented so you all can help me figure this out.



All of these brews were All Grain brews, mashed around 151-155. I used a thermapen to check temperatures (so they should be pretty accurate).
Now, I did like these beers tremendously – I just keep thinking the FG should be a little lower. I believe that I have read dry yeast ends around 1.020 but then I have read that isn’t necessarily true.

Anyways, if someone can give me some insight that would be great!

Thanks,
Scott

Have you checked your hydrometer to see if it's reading SG correctly?

Check to make sure the thermapen is still accurate. Just because it's a thermapen doesn't guarantee it won't need to be calibrated/corrected from time to time. Pick up a good lab grade liquid thermometer to use as a reference.These can often be found for pretty short money.

Also, check the batteries in the thing. Or replace the batteries and see how it performs.

Mash temp, percent of unfermentable sugars (such as in darker malts) & fluctuations in fermentation temperature all can effect FG. I've not had any problem with 05 or Notty getting down to 1.010 or less if these factors are controlled so I wouldn't think that it's related to dry yeast.

I like to ferment my ales in the low 60s, but to get them to finish out, I ratchet up the temps 1f per day or so, until after about a week I'm at the top end of the recommended range for the yeast. I usually see a drop of anywhere from 4 to 10 gravity points doing this. I also will rouse the yeast a bit if I feel like a beer is stuck, but I make sure to wait for the increased temps to get the airlock going again so I know there's no O2 left in the fermenter from the last time I took a sample.

I agree with the hydrometer maybe being out of calibration. Easy enough to check with distilled water. FWIW, my RO and tap water and distilled all read the same.

Mash temp seems pretty reasonable. Are there a lot of non-fermentables in those recipes? Are these 5 gallon batches? If larger it's possible you're under pitching yeast. But five gallons even at 1.074 should only need a little over one 11.5g pack of yeast.

I've had the same experience as the OP. but with white labs yeast. I've noticed that after four weeks at ambient 61F the beer is still fermenting. With wlp001, wlp002, wlp300, and kolsch ale yeast. Never had the problem when ambient was at 68f but the taste is cleaner now.

Have you checked your hydrometer to see if it's reading SG correctly?

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yes, the hydrometer is reading correctly.

Check to make sure the thermapen is still accurate.

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I will check with freezing and boiling tests tonight

I like to ferment my ales in the low 60s, but to get them to finish out

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I do this as well, this could very be part of the issue

Are there a lot of non-fermentables in those recipes? Are these 5 gallon batches? If larger it's possible you're under pitching yeast. But five gallons even at 1.074 should only need a little over one 11.5g pack of yeast.

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they are 5 gallon batches, not really any non-fermentables

scottvin said:

I will check with freezing and boiling tests tonight

they are 5 gallon batches, not really any non-fermentables

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Also check it at the mash temp area/range. Digital thermometers can be good at the extremes, but not so much in the range we mash at.

Post up the recipes of the batches that didn't finish right (in your opinion). There's pretty much always non-fermenting items, or less fermenting items, in recipes. Unless it's a SMaSH that was mashed around 148F that is.