Stuck fermentation at 1.029

[neudson]

I am brewing a Imperial IPA, with a OG of 1.082, using DME and steeped grain of Crystal and Amber malts, using Safbrew T58 for fermenting. After 2 weeks it got to 1.029. Yesterday, 4 days later, i had another reading and is still stuck at 1.029. These last four days it has been fermenting around 20 and 23ºC.

I stirred the yeast back in suspension and put it back to fermenting at the same temperature.

In case i do not get the yeast to work again, not even repitching, it would be to high of FG this 1.029?

 

[hercher]

Its hard to say, without your exact recipe and process. But it is possible you are done at 1.029. I have a stout on tap now that finished at 1.026. Remember, your crystal and amber malts are not adding any fermentables. You could try finishing your beer with some wine or champagne yeast if you want a drier finish.

 

[cluckk]

1.029 is higher than the guideline for your style. That yeasts minimum attenuation should put you at 1.023 and the max attenuation should put you around 1.020. Your temperature looks good.

To know anything we really need more information. How much yeast did you pitch? Did you aerate your wort? If so, how long? With pure oxygen or atmosphere? What sanitizer did you use? etc. The more information about your products and procedure the better.

 

[neudson]

I used 500g Amber Malt and 250g Crystal 150L for steeping. And then added 2kg of DME Amber and bring to boil. Boiling for 60 minutes, adding hops. Cool it, added yeast (safbrew T-58) with the wort at 23ºC. It fermented at this temperature for the first 12 hours than i brought it to below 20º. After 24h it was at 1.040ish. After a week at 1.036. After 2 weeks at 1.029. All this time fermenting below 20º. I brought the temperature up again for the third week, then got another reading yesterday, 4 days afters the last one. The expected FG calculated by Brewersfriend was 1.023.

I really think that it could have been done fermenting by now. But as I stirred, I'll give it a couples days to settle again and then proceed to bottle if its still at 1.029.

 

[neudson]

I was even afraid i had overpitched. I used two packages dry yeast for a 2,5 gallon recipe. I did aerate a lot (three not planned bucket transfers lol). I basically used bleach for sanitizing.

 

[WoodlandBrew]

Are you using a refractometer?

Here are the top ten reasons you final gravity may be stuck:
http://woodlandbrew.blogspot.com/2012/11/top-ten-reasons-why-your-final-gravity.html

 

[neudson]

Are you using a refractometer?

No, i'm using a hydrometer to make my readings.

 

[WoodlandBrew]

What type of crystal and how much? Crystal L40 is only about 70% fermentable when mashed, and even less when steeped, but if it is less than 10% of the grist it's pretty negligible.

 

[neudson]

What type of crystal and how much? Crystal L40 is only about 70% fermentable when mashed, and even less when steeped, but if it is less than 10% of the grist it's pretty negligible.

I used half pound of Crystal 150, 1 pound of Amber Malt, both steeped, and 4,5 pounds of DME Pale. This for a 2,5 gallong batch.

 

[WoodlandBrew]

I used half pound of Crystal 150, 1 pound of Amber Malt, both steeped, and 4,5 pounds of DME Pale. This for a 2,5 gallong batch.

It might be the combination of the crystal not being mashed, and the DME not fermenting well.

Crystal 150 is about 55% fermentable when mashed, and less fermentable when steeped. I'll guess that's it's 30% fermentable. Let's also guess that you are on the low end of fermentability for the yeast beacuse it is trying to work through DME. That's about 71%.

OG calculations:
Crystal: 0.5lbs * 34pppg = 17 GU
Amber malt will provide no sugar, just color
Pale DME: 4.5lbs * 44pppg = 198 GU
(17+198)/2.5= 86 GP or 1.086

FG calculations:
Crystal: 17 * 70% = 12
DME: 198 * 29% = 57
(12+57)/2.5=28 GP or 1.028

For an explination on how I do final gravity calculations see this:
http://woodlandbrew.blogspot.com/2012/12/final-gravity-in-recipe-formulation.html

 

[neudson]

It might be the combination of the crystal not being mashed, and the DME not fermenting well.

Crystal 150 is about 55% fermentable when mashed, and less fermentable when steeped. I'll guess that's it's 30% fermentable. Let's also guess that you are on the low end of fermentability for the yeast beacuse it is trying to work through DME. That's about 71%.

OG calculations:
Crystal: 0.5lbs * 34pppg = 17 GU
Amber malt will provide no sugar, just color
Pale DME: 4.5lbs * 44pppg = 198 GU
(17+198)/2.5= 86 GP or 1.086

FG calculations:
Crystal: 17 * 70% = 12
DME: 198 * 29% = 57
(12+57)/2.5=28 GP or 1.028

For an explination on how I do final gravity calculations see this:
http://woodlandbrew.blogspot.com/2012/12/final-gravity-in-recipe-formulation.html

Thanks, WoodlandBrew!
So I think we really got to the end of fermentation. I'll just check the gravity again tomorrow. If it's at .1029 again, then I think i will cold crash it for a couple of days, to help settle the yeast again, and the bottle next week.

But just out of curiosity..is not the yeild for the Crystal of 34pppg too high for steeping? When I did my calculations I used something like 16ppg, based on that John Palmers Yeild reference chart, and got closer to my OG that was 1.082.

 

[WoodlandBrew]

That's likely true. I would go by what Palmer said, but I guess that leaves a few points un accounted for.