Dividing line between close enough and stuck fermentation?

[chaps]

I recently brewed a Porter with a OG of 1.053 and an expected FG of 1.015 (its gluten free). After two weeks of fermentation I am sitting at 1.025 with two readings 3 days apart. If i was at 1.020 or lower i would say close enough and bottle. 10 points off seems kind of far as well as a risk of bottle bombs or gushers. Thoughts on how far off you get before "close enough" becomes "figure out plan B"?

 

[urg8rb8]

I recently brewed a Porter with a OG of 1.053 and an expected FG of 1.015 (its gluten free). After two weeks of fermentation I am sitting at 1.025 with two readings 3 days apart. If i was at 1.020 or lower i would say close enough and bottle. 10 points off seems kind of far as well as a risk of bottle bombs or gushers. Thoughts on how far off you get before "close enough" becomes "figure out plan B"?

All grain? Extract?

 

[Gnomebrewer]

If you have the issue regularly, try doing forced ferments. I find the easiest way is to take about 200mL of beer at high krausen and add a good dollop of yeast from the krausen, then sit it somewhere nice and warm (about 80 to 85F is good for most ales). Swirl it every now and then. If you main beer finishes more than a couple of points above your forced ferment, you have an issue.

 

[chaps]

All grain? Extract?

Partial mash. Grain and sorghum extract.

 

[chaps]

If you main beer finishes more than a couple of points above your forced ferment, you have an issue.

Cant do this unfortunately. Wasn't much krausen. Thankfully though I'm 18/20ish for good fermentation and numbers finishing close-ish to expectation (+/-5)

But thats my real question: if you had to put a number to it, how many points is a 'couple of points'? 5? 8? 10?

 

[Gnomebrewer]

But thats my real question: if you had to put a number to it, how many points is a 'couple of points'? 5? 8? 10?

A couple of points for forced ferment to main ferment is 2 points. Points for expected to final gravity would be a bit higher, and be dependent on the beer. A 1.050 beer using US05 yeast on a single temp mash at 152: I'd be concerned if I was more than 2 points out. A 1.080 beer with steps at 143 and 160 and a dose of sugar using an unfamiliar yeast? Harder to predict accurately so 6 to 8 points, maybe even 10 points, from expected might be acceptable.

 

[BrewnWKopperKat]

Cant do this unfortunately. Wasn't much krausen.

There are similar forced ferment test approaches (http://www.brewunited.com/index.php?blogid=112 is one) that add yeast to the sample.

 

[chaps]

A couple of points for forced ferment to main ferment is 2 points. Points for expected to final gravity would be a bit higher, and be dependent on the beer. A 1.050 beer using US05 yeast on a single temp mash at 152: I'd be concerned if I was more than 2 points out. A 1.080 beer with steps at 143 and 160 and a dose of sugar using an unfamiliar yeast? Harder to predict accurately so 6 to 8 points, maybe even 10 points, from expected might be acceptable.

Thanks that totally answered my question. 10 points is too far off since its a lower gravity beer with a generic but hardworking yeast.

 

[chaps]

So a follow-up incase anyone stops by in the future to see what happened:

• I shook the fermenter vigorously, turned up the temp in the fermentation chamber to 80 degrees, and left it for another week per instructions gathered on "the internet".
• After a week the gravity had only gone down 2 points and so I bottled at 1.023 I thought either it was done fermenting or due to the annoying nature of gluten free grains perhaps some of the stuff didn't get converted into sugar.
• After letting it carbonate at 75 degrees for two weeks I opened a swing top... gusher. Total gusher.

Next time i think i will try sterilizing some sugar and throwing that in the fermenter for a week and see if that helps 'kick-start' a second fermentation process.