Yet another - my beer seems to have stopped fermenting after a couple of days...

So, I am still relatively new to home brewing, I only started last March, but have probably brewed about 25 batches so far. I've had a couple gone bad but all I know the reason why.

Here is my latest batch. It is a Amber Ale, done BIAB mashed at 151f for 75 minuets. It's the first BIAB that I have not done a mash out on.

My starting gravity was 1.057 and I pitched two packages of Wyeast 1332 Northwest Ale yeast @70f, which I have used a number of times on other batches. The fermentation was going in under 7 hours. As per usual I keep a daily eye on fermentation and I noticed that 4 days later not only had my fermentation seemed to stop but my beer was clearing very quickly. My temps had dropped about 5 degrees. I took a reading on it and I came up with a 1.032 gravity reading. I've moved the carboy up to a warmer spot, but it just seems really odd that this stopped so quickly.

So before I get into my questions, I am super meticulous about cleaning. I use both PBW and/or StarSan to clean all of my vessels and equipment. Yes, I know I probably shouldn't fret about this, but I have never had a batch go like this.

So the big question is what did I screw up and what can I change? Any ideas on how to fix?

the temperature drop could have cause the yeast to drop out but seems unlikely at 65° - warming it up is def the right move here, maybe a gentle swirl as well

if it is indeed done at 1.032 it could be either a result of your recipe (too many unfermentables) or perhaps your thermometer was off and you mashed much higher than 151°

What kind of thermometer are you using to measure your mash temp? Is it well calibrated?

What is your recipe? Are you sure you used the grains you think you used?

How did you aerate or oxygenate?

And less likely for this problem, as 1.032 is way off from a normal finishing gravity for this style, but have you calibrated your hydrometer?

Thanks for your prompt responses. I am using a Blichmann Boilermaker kettle with a brewmometer. I have not gone back and re-calibrated it since I got the pot, but it seems spot on. I've checked it with my other lab thermometer and my cooking candy thermometer, and the are all within 1 degree of each other.

My malt bill is as follows.... all grains were fresh from Northern Brewer (retail store) and I milled them twice.
12lb Briess Mild Ashburne
1lb Carmel 40
.75lb Victory
.5lb Munich
.25lb Carmel 120
.25lb Carared

I am not using a hydrometer, but a Refractometer, which is calibrated.

RustyPitchfork said:

I am not using a hydrometer, but a Refractometer, which is calibrated.

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I'll ask the easy question first. Did you also correct the final refractometer reading based on your OG?

StoneHands said:

I'll ask the easy question first. Did you also correct the final refractometer reading based on your OG?

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Do you mean adjust my refractometer for the the proper temp at reading? Yes.

I thought you can't use a refractometer for checking gravity after alcohol is being produced because it skews the light coming in. This is what I found while doing research when I was looking to purchase one. What I read was to use it on brew day and a hydrometer after fermentation starts.

RustyPitchfork said:

I am not using a hydrometer, but a Refractometer, which is calibrated.

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Oh, that's it. Run and check it with a hydrometer. Trust me!

We'll wait- and when you report back we can help if it's actually stuck (and it's not).

OG of 1.057 and current refractometer reading of 8 brix is 1.016 when corrected for the effect of alcohol on the reading.

Well, that might just be it! My hydrometer reading says 1.014. Can someone explain why such a great difference in the readings?

RustyPitchfork said:

Well, that might just be it! My hydrometer reading says 1.014. Can someone explain why such a great difference in the readings?

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Refractometer measure the refractive index (how the liquid bends light). It converts the refractive index of a sugar water solution into a gravity. But alcohol had a different refractive index than sugar water, so it throws off the reading.

So measure with a refractometer when it's wort and the the hyrdometer when it's done fermenting?

RustyPitchfork said:

So measure with a refractometer when it's wort and the the hyrdometer when it's done fermenting?

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Yes.

RustyPitchfork said:

Well, that might just be it! My hydrometer reading says 1.014. Can someone explain why such a great difference in the readings?

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I could explain it scientificly, wait no, I can't. It just is. It has something to do with how light is refracted (sorry to sound stupid just stating the obvious).

Rule of thumb is don't use refractometer when alcohol is present. Hydrometer all the way.

Thanks everyone! If nothing else, I can say I learned something today.

RustyPitchfork said:

So measure with a refractometer when it's wort and the the hyrdometer when it's done fermenting?

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Or convert using a brewing calculator. But hydrometer is most accurate, since it's closer to measuring what you actually want.

Fyi, water has an r.i. of 1.33, ethanol is 1.36, and sugar increases r.i of water, which is why alcohol makes it look like there's more sugar per the refractometer.