HELP: WLP540 Abbey IV Attenuation

[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.

 

[Calder]

Let it rise to your house temperature, and see what happens.

Check the accuracy of your thermometer, if you mashed high the wort will be less fermentable. 1.023 does seem high. Have you check FAQs on that yeast; some Belgian yeasts take a long time to finish.

I also like to add a large amount of simple sugar (20 to 25%) to my Belgians to help them really dry out.

Checking thermometer temp is easier said than done. I usually get several thermometers and place them in a large container of hot water (around the temp I am concerned about), and see if they all read the same. Just checking 32 F (ice water) or 212 F (boiling water), doesn't tell you what it does at other temps. If you check at both, you should be good.

I have one thermometer (electric read thermometer), which is OK at 32 F, OK at Room Temperature, but is off about 7 degrees when you get to about 150 F.

 

[ultravista]

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

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 80F.

I would be ecstatic if it dropped another 10 points.