When to Re-Pitch Yeast

[Andrew82]

I put an IPA into primary on the night of 3/3. The beer had a lag time of about 8-9 hours and gradually started fermenting increasingly vigorously. Last night it was fermenting furiously.

This morning it has totally stopped.

Characteristics of brew:

• The wort is 3.5 gallons, so I pitched slightly (70%) of a full packet of Safale S-04 rehydrated in 237ml water.
• Pre-boil gravity = 1.051; Post-boil OG = 1.060
• The wort water is ion-exchanged through a Brita-like filter.
• I used no yeast nutrients.
• The wort aeration was provided by letting the wort splash out of the Megapot kettle into the fermenter.
• The temperature doesn't seem to have changed dramatically.

I've wrapped the fermenter in a blanket. But should I reconsider repitching or just adding yeast nutrients? If so, how much?

 

[J A]

It's almost certainly done. S-04 works fast when it gets going and then it stops and drops. Take a gravity reading and if it's substantially higher than expected, give the fermenter a swirl. You didn't mention temperature but just be sure that it stays in the mid-60s for the duration, not cooler.

 

[Andrew82]

It's almost certainly done. S-04 works fast when it gets going and then it stops and drops. Take a gravity reading and if it's substantially higher than expected, give the fermenter a swirl. You didn't mention temperature but just be sure that it stays in the mid-60s for the duration, not cooler.

Wow! You were absolutely right. Gravity reading from the hydrometer puts it around 1.011. Refractometer looks like 7.5 brix which I guess puts that reading at 1.028, but I understand that alcohol distorts the refractometer readings, so I'll take the hydrometer reading.

Should I maintain the fermentation schedule (2 weeks in primary) as is despite the faster-than-expected fermentation?

Thank you for your advice.

 

[J A]

Should I maintain the fermentation schedule (2 weeks in primary) as is despite the faster-than-expected fermentation?

Not necessarily. That yeast is perfectly capable of finishing fermentation in a few days, but it could go lower than 1.011 over the next few days. I'd leave it for a week total and then check again. If it's the same, proceed to crashing/packaging, etc. If it's lower, check it after one more day just to be sure you're getting at least a couple of consistent readings and then move on with the process.

 

[Andrew82]

Following up on this thread. I just put the IPA into bottles.

So I got the same SG reading consistently, it even went down to 1.008 based on my hydrometer reading. I kept the beer in the fermenter based on my reading of Palmer's discussion of the yeast's Conditioning Phase in "How To Brew." I dry-hopped on 3/10 and, based on my previous SG readings, bottled today.

Here's the kicker: I took a hydrometer and adjusted (Beersmith) refractometer reading: 1.020 FG and .961 FG, respectively. I have no idea what could have happened. Is it that I simply took a bad reading with the hydrometer the first two times?

Also, how is it possible that the two readings using two different instruments were so different?

 

[Nosybear]

Following up on this thread. I just put the IPA into bottles.

So I got the same SG reading consistently, it even went down to 1.008 based on my hydrometer reading. I kept the beer in the fermenter based on my reading of Palmer's discussion of the yeast's Conditioning Phase in "How To Brew." I dry-hopped on 3/10 and, based on my previous SG readings, bottled today.

Here's the kicker: I took a hydrometer and adjusted (Beersmith) refractometer reading: 1.020 FG and .961 FG, respectively. I have no idea what could have happened. Is it that I simply took a bad reading with the hydrometer the first two times?

Also, how is it possible that the two readings using two different instruments were so different?

First, 0.961 in beer is just about impossible. Try that reading again.

 

[J A]

Refractometer readings of finished beer are very inaccurate. I wouldn't bother.
The most likely reason for a reading that high at bottling is that the hydrometer was sitting on the bottom of the container. Even if you took a reading after priming, there'd only be a couple of points difference.

 

[Nosybear]

Refractometer readings of finished beer are very inaccurate. I wouldn't bother.
The most likely reason for a reading that high at bottling is that the hydrometer was sitting on the bottom of the container. Even if you took a reading after priming, there'd only be a couple of points difference.

They're inaccurate if you're looking for an absolute measure. If all you're looking for is difference, they work fine, uncorrected. Since the chemistry is consistent, with good correction software like the correction calculator on this site, I find my refractometer is more accurate than a hydrometer. But you're right, there is something way off in the reading. One thing that can happen with a refractometer: The sample is so small, if you don't take measures to make sure your dropper is clear of any water, you can dilute the sample, skewing the reading.