[ultravista]

On 09/05, I brewed a Rochefort 8 - mashed at 149F, with an OG 1.087, aerated with O2, pitched with a 3L starter of WLP540 Abbey IV, and fermented at 71-72F. Beersmith estimated this to land somewhere near 1.010.

Exactly a month later, it is at 1.023 despite rousing the yeast, bumping to 74F, and adding leftover yeast from the 3L starter.

Beersmith calculates 1.087 > 1.023 as 71.9% apparent attenuation. White labs states 74-82% attenuation.

At this point, it is a bit too sweet, and I don't know what else to do to bring it down.

Should I perhaps bring it up a few more degrees and rouse the yeast again? If yes, how high should I go at this point? Ambient house temperature is approximately 78 F.

[HoosierBrew]

Should I perhaps bring it up a few more degrees and rouse the yeast again?

Yeah, I would. No major worries with the temp now  - the first several days would've determined the flavor profile. Give it a gentle rouse and warm up near 80F for several more days. I hope it helps. Let us know !


EDIT  -  Also, did you use a hydrometer or refractometer to measure FG ?  Using a refractometer for FG requires a correction to account for the alcohol present. Just wondering, in case you got a bad reading.

[ultravista]

I use a Thermapen thermometer for the mash and testing with two hydrometers. Both read exactly the same.

[brewinhard]

Did you provide the wort with proper aeration when pitching your yeast?  Was your grain bill heavy on specialty malts that might reduce attenuation?

[ultravista]

Aerated with 02 for about a minute. Specialty malts were low, primarily 2-row. I did use 2 # of Candi Syrup's D180 at the end of the boil.

I have since re-roused the yeast and moved the thermostat to 78F.

I would be ecstatic if it dropped another 10 points.

[HoosierBrew]

Aerated with 02 for about a minute. Specialty malts were low, primarily 2-row. I did use 2 # of Candi Syrup's D180 at the end of the boil.

I have since re-roused the yeast and moved the thermostat to 78F.

I would be ecstatic if it dropped another 10 points.

Given your recipe and process I would think it'll drop some more points. I'll be curious to see how you come out. Good luck !

[egg]

How's this going?

I have a Holtrop-ish Rochefort 8 on the go too, 21 liters OG 1.079, with the WLP 540 (700ml stepped to 3.5L starter) which is at 1.016 after 2.5 weeks, sat at 76F (pitched at 63) having been roused several times.  It looks to be going no lower, so about 80%AA.  My adaptations led to 15% sugar in total and the mash was 2.5hrs at 147, with a brief mash out to follow.

Going by Stan Hieronymous' figures for OG and attenuation, it looks like the real thing finishes around 1.008/9.  I wish I could get it down there.  Tastes great, but a 1.016 body with 3.5vols plus of CO2 will be a pretty full mouth feel.  I guess I've just got to mash even lower next time.

[morticaixavier]

How's this going?

I have a Holtrop-ish Rochefort 8 on the go too, 21 liters OG 1.079, with the WLP 540 (700ml stepped to 3.5L starter) which is at 1.016 after 2.5 weeks, sat at 76F (pitched at 63) having been roused several times.  It looks to be going no lower, so about 80%AA.  My adaptations led to 15% sugar in total and the mash was 2.5hrs at 147, with a brief mash out to follow.

Going by Stan Hieronymous' figures for OG and attenuation, it looks like the real thing finishes around 1.008/9.  I wish I could get it down there.  Tastes great, but a 1.016 body with 3.5vols plus of CO2 will be a pretty full mouth feel.  I guess I've just got to mash even lower next time.

with 15% sugar and a 147 mash temp you should be able to get 1.079 down to 1.008 without a problem.

starter size sounds sufficient too. If you mash too much lower you'll drop out the bottom of the alpha range and won't get as fermentable a wort because the alpha amylase won't be breaking the longer chain sugars to allow the beta amylase to nip off the ends.

[HoosierBrew]

How's this going?

I have a Holtrop-ish Rochefort 8 on the go too, 21 liters OG 1.079, with the WLP 540 (700ml stepped to 3.5L starter) which is at 1.016 after 2.5 weeks, sat at 76F (pitched at 63) having been roused several times.  It looks to be going no lower, so about 80%AA.  My adaptations led to 15% sugar in total and the mash was 2.5hrs at 147, with a brief mash out to follow.

Going by Stan Hieronymous' figures for OG and attenuation, it looks like the real thing finishes around 1.008/9.  I wish I could get it down there.  Tastes great, but a 1.016 body with 3.5vols plus of CO2 will be a pretty full mouth feel.  I guess I've just got to mash even lower next time.

+1 to Jonathan's comments. I wouldn't mash lower than that. Are you measuring your FG by hydrometer or refractometer? If hydrometer, is it reading accurately ? If refractometer, did you do a correction for the abv present ? I agree that if you roused and it's been @ 76F that it's probably done.

[S. cerevisiae]

Beersmith calculates 1.087 > 1.023 as 71.9% apparent attenuation. White labs states 74-82% attenuation.

If Beersmith is telling you that 1.087 to 1.023 is 71.9% apparent attenuation, then there is a bug in Brad's software. 

AA = (O.G. - F.G.) / (O.G. - 1) x 100 (multiplying by 100 yields AA as a percentage value instead of as a fraction)

AA = (1.087 - 1.023) / (1.087 - 1) x 100 = 73.6%  (which is the lower end of the given range for the strain)

Here's a clear cut example of why it is important for all brewers to learn basic brewing mathematics before using brewing software.

[narvin]

In limited experience, I've also seen "underattenuation" (at least in terms of what Rochefort gets) with the first generation of this yeast.  Doing a 6 -> 8 -> 10 clone series repitching from one to the next resulted in much better attenuation.

[S. cerevisiae]

Was it a single-step or a two-step starter? What was your starter gravity? 

A lot of brewers make the mistake of brewing a big beer with yeast grown in 1.040 gravity wort.  Pitching a culture grown in 1.040 wort into 1.087 wort seriously stresses the yeast cells.   A better approach is to pitch the vial into 1L of 1.030 gravity wort, wait twelve to eighteen hours, chill and decant the supernatant (a.k.a the clear liquid that lies above the slurry), and then pitch the slurry into 3 liters of 1.060 wort.  Using this process, we are also increasing osmotic pressure with each step.

[egg]

In limited experience, I've also seen "underattenuation" (at least in terms of what Rochefort gets) with the first generation of this yeast.  Doing a 6 -> 8 -> 10 clone series repitching from one to the next resulted in much better attenuation.

This makes sense.  With WLP 530, I've had tripels drop as far as 1.085 to 1.009 with 13% sugar (I've never harvested and repitched yet) and a 150F mash.  Looking around, 540 seems like a very different animal.

Not sure if it's a consideration for the OP too, but I'm considering krausening-in some US-05.

[narvin]

A lot of brewers make the mistake of brewing a big beer with yeast grown in 1.040 gravity wort.  Pitching a culture grown in 1.040 wort into 1.087 wort seriously stresses the yeast cells.   A better approach is to pitch the vial into 1L of 1.030 gravity wort, wait twelve to eighteen hours, chill and decant the supernatant (a.k.a the clear liquid that lies above the slurry), and then pitch the slurry into 3 liters of 1.060 wort.  Using this process, we are also increasing osmotic pressure with each step.

There are no hard and fast rules, but I would say that in most cases the mistake is making a high gravity starter.

The starter was well within the ratio of growth (4X at most). The gravity was low, the way every yeast lab propagates yeast.  The idea is that you can pitch the correct number of cells, grown in ideal conditions (LOW GRAVITY WORT).

Whether or not this is always true is another deal.  540 is one of the few where I've had any problem at all with starter grown yeast.  However, I would never encourage someone to make high gravity starters.  But obviously certain yeasts benefit more than others from growing in brewing conditions.

[ynotbrusum]

I always wait to pitch my candy sugar until at least high krausen for this reason.  Not based on science at all, just based on general observation....don't give the yeast the dessert until they pretty much are finished with dinner.  I may have just been a lucky SOB, but I get almost all Belgians to finish well into the upper range attenuation stated for the yeast.