Out of control US05

[tnbrewer371]

Okay so I just had some safale us05 slurry (harvested from a batch of blonde ale) take an imperial IPA from 1.093-1.009 which is 90% attenuation. Any one know how this is possible? Obviously this isn’t ideal in this instance. As a matter of fact I’ve been getting 85%+ attenuation with us05 fairly consistently. Ideas as to what could be going on?

 

[tnbrewer371]

Last three beers from my notes have been 90%, 93%, and 92% attenuation.

 

[Dland]

I regularly start at around 1.060 and get down to 1.008. Perhaps your attenuation % is so high because your starting gravity was so high, as the final SG is pretty normal.

 

[downzero]

What was your mash temperature and what did you expect your FG to be? 11% abv is no joke!

 

[BruceH]

US-05 usually takes my brew to 1.008. This is for something starting at 1.05x. I think it has to do with the temps I mash at. Repitching slurry makes the whole fermentation go crazy fast. Some day I'll get a little more scientific about repitching.

What were you expecting for FG?

 

[tnbrewer371]

I was expecting a FG if 1.019. So it’s a bit thin. I haven’t tasted it carbed yet, but the sample from the bucket wasn’t hot. It just seems 90%+ average attenuation is high for this yeast, maybe I’m wrong. Idk. I’m going to start mashing higher and see if I can get it to flatten out.

 

[grambo]

What temperature are you mashing at? Are you mashing out, and are you starting the boil immediately after (or during) sparging?

I was getting very high attenuation due to mashing too low and failing to mash out during sparging... But 80s, not 90s. Consistent 90s sounds pretty wild. Any off flavors that indicate contamination? Even if you're pitching fresh yeast, there could be Brett in your transfer lines or something.

 

[tnbrewer371]

I am not mashing out that must be the culprit bc I switched to skipping a mashout step a few months back to increase my sparge water volume. But yes I boil immediately after I runoff

 

[tnbrewer371]

I feel like such a Rookie for not making that connection. That has to be the culprit.

 

[day_trippr]

fwiw, I did a barleywine years ago, pitched us-05 into highly-fermentable 1.090 wort then after 48 hours started adding a half pound of dextrose each day. Once the abv calculated to 14% I pitched wlp099 and continued to 18%. So at least under very specific conditions one can drive us-05 well above it's comfort zone...

Cheers!

 

[dmtaylor]

My guess is it's a calibration issue -- both calibration of your hydrometer and your mash thermometer. When's the last time you've calibrated each? If for example your hydrometer is reading 4 points low in plain water (0.996) then you would need to add 4 points to all of your hydrometer readings, in which case you might actually have OG 1.097 and FG 1.013, which would give a more reasonable attenuation of 86%. And if your mash thermometer reads a little high and you've actually mashed say 4 degrees cooler than you thought, this could also increase attenuation i.e., lower FG. Have you calibrated your mash thermometer in boiling water adjusted for your elevation? For example here in Wisconsin we are 600 feet above sea level so water actually boils at 211 F instead of 212 F. For every ~500 feet elevation, boiling point is about a degree lower. So then if my thermometer reads for example 216 F in boiling water, I know it's high not just by 4 F but by 5 F here, and then when I think I'm mashing at 152 F, I might actually be mashing at 147 F.

These are just examples. But look into it.

P.S. Mashing out or lack thereof is NOT a significant player IMO.

 

[kh54s10]

Regarding mash out. It depends on your sparging method. I do a double batch sparge. It takes a total of about 15 minutes. I have never done a mash out and have never had an attenuation problem like described. If you fly sparge and it takes an hour, it might make a difference skipping the mash out. But I don't think it would be so drastic.

I have seen that second use of yeast yields a better attenuation from the initial pitch, but again, not that much.

 

[tnbrewer371]

All good points y’all. Thanks. I think I def will check into calibrating my hydro and therm. And go from there. Stand by for updates. I appreciate all the help this forum provides, ive been brewing consistently for 11 years and occasionally forget that sometimes the simplest solution is the right one....