High attenuation with WLP001?

[sboyajian]

Few weeks back I brewed my pumpkin ale. I hit all of my numbers and my OG came in at 1.068. I got the temp down using my wort chiller and pitched the yeast (WLP001 California Ale) at 70F on the dot. My basement stays exactly 70F so it's been there the whole time without fluctuation.

I have a very active first few days and had to move over to a tube since the airlock was filling up with kraussen. It remained active for what seemed like forever and after 2 weeks I went to check on it and noticed that my FG was 1.004. I was expecting about 1.016.

At first I thought "Did it get infected??" but it seemed clean. It smelled fine, the top only had some lingering yeast rafts, and everything looked good. I closed it up and let it sit a few more days to clear out, checked on it again, OG is the same, so it hasn't dropped anymore.

I've seen other people report attenuation of 85-90% of the WLP001 before, but 94% seems crazy. If it's not infected, aside from being a bit dryer, should I be worried? Clearly it's still beer, and hopefully it tastes great, but I've never experienced this before.

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TL;DR - 94% attenuation with WLP001. No signs of infection. What should I expect?

 

[sboyajian]

Meant to post this in Fermenation/Yeast.. sorry bout that..

 

[jakwi]

Take a sample , if it tastes good bottle and save some of that yeast! the other possibility is that you made a mistake on your og measurement.

 

[MattGuk]

Did you make a starter? If so, how big of a starter?
Also what was your ferm temp?

 

[sboyajian]

Although I should have made a starter, I did not. I just pitched the yeast into the bucket.

Temp was between 70-72 at all times. Usually 70, but a couple of times it did get to 72.

 

[duboman]

Not sure how you are getting apparent attenuation of 94%

(OG-FG)/(OG-1) x 100 = apparent attenuation
(68-16)/(68-1) x 100= 78%

This would be in line with what I would expect

EDIT: Oops, mis-read the post, you are correct, assuming the FG was 1.004 you did in fact get 96%! Was this an all grain batch and if so what did you mash at? A very low mash temp would have created a very fermentable wort resulting in a lower than expected FG

 

[CastleHollow]

^78% was what he expected, but his FG was 1.004.

OP, was this a PM or AG? What was your mash temp? I assume you're measuring with the same hydrometer?

 

[duboman]

^78% was what he expected, but his FG was 1.004.

OP, was this a PM or AG? What was your mash temp? I assume you're measuring with the same hydrometer?

Saw that, that's why I edited my post and asked the same question

 

[sboyajian]

It was AG. I mashed at 154F for an hour using 168F water. Was supposed to be 156, but I guess the grains dropped it couple more than I expected. After the hour in the cooler mash it was still 151. Then I fly sparged with 168F.

151-154 was a bit lower than I wanted, but I wouldn't think 2-3 degrees would make that much difference, would it?

 

[sboyajian]

^78% was what he expected, but his FG was 1.004.

OP, was this a PM or AG? What was your mash temp? I assume you're measuring with the same hydrometer?

Yep, I've only got the one and it measures 1.000 in water, so I know it's not giving me a totally wonky reading.

 

[duboman]

It was AG. I mashed at 154F for an hour using 168F water. Was supposed to be 156, but I guess the grains dropped it couple more than I expected. After the hour in the cooler mash it was still 151. Then I fly sparged with 168F.

151-154 was a bit lower than I wanted, but I wouldn't think 2-3 degrees would make that much difference, would it?

Are you sure your thermometer is calibrated? I would expect a mash temp in the 148oF range for that high attenuation, that could be the issue

 

[sboyajian]

Are you sure your thermometer is calibrated? I would expect a mash temp in the 148oF range for that high attenuation, that could be the issue

Now that is a good question. I usually use digital, but the battery died and I used an analog.

I'll have to check tomorrow to see if the numbers match up.