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TropicThunder

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I just bottled an Imperial IPA and I didn't hit the attenuation numbers I was hoping for, so I'm hoping you have some ideas! It was disappointing because in the past the same setup on smaller beers attenuated properly. Here's the recipe.

Style: American Imperial IPA
Malts
9.9 lbs. LME
1 lb. Corn Sugar
1/2 lb. Crystal 10L

Hops
4 oz. Cascade
4 oz. Citra
1 oz. Magnum

Yeast
2 packs Fermentis US-05

Water
1 gallon store-bought distilled
~4 gallons filtered sink water

Basement Temp: 66 degrees
OG: 1.084
FG: 1.029 (expected 1.018)
ABV: 7.35% (expected 8.79%)
Apparent Attenuation: 66% (expected 75-80%)

Procedure: I steeped the Crystal malt between 140 - 160 degrees for 20 minutes. Then I brought it up to a boil, took it off the heat and added 3.3 lbs. LME. At 45 minutes I added the corn sugar and 6.6 lbs. LME. At flameout (60 minutes) I cooled it to 80 degrees in the sink with an ice bath, poured it into the fermentor that already had water in it (which was room temp), then topped it off to 5 gallons. I stirred vigorously for 5 minutes (lots of froth on top), then swirled the wort and dropped in the dry yeast, a little at a time. Gravity was measured (both times) with a hydrometer. It was then stored in a dark room in my basement.

At 2 weeks I dry hopped it and 4 days later I bottled. I was surprised to see that the yeast hadn't performed as well as it has for me in the past. Following the same method above, I regularly get 80% apparent attenuation on beers with OG 1.060 and below.

Any idea what I could change in the future to help this one out? I don't usually use more than one pack of yeast, but I also don't regularly make bigger beers. I'm stumped - where could this have gone wrong? I'm thinking of adding yeast nutrient next time, but I haven't had to do this in the past. Thoughts?
 

Rob2010SS

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The things that come to mind are...

(1) Was the beer aerated thoroughly? Yeah you stirred it but was it enough?
(2) Was it actually done fermenting? Did you take consecutive gravity readings and it was the same?
 
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TropicThunder

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(1) Was the beer aerated thoroughly? Yeah you stirred it but was it enough?
(2) Was it actually done fermenting? Did you take consecutive gravity readings and it was the same?
1) I stirred it like the other batches I've done in the past and have had good luck with, but this was a higher gravity than I've done before. Other than getting a device to aerate the wort, are there other techniques? I was thinking of passing it through a fine strainer when I put it into the fermentation bucket, that ought to help, right?
2) I didn't take more than the OG and FG readings (though I should have when I dry hopped to check it out). Hope I don't have bottle bombs now! In the past I've always let brews go for 2 weeks before bottling. Would the yeast have stalled then kicked back into gear later?
 
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TropicThunder

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As for question #2, I could probably wait for a few days, crack a bottle and then measure again, right?
 

Tribe Fan

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1) I stirred it like the other batches I've done in the past and have had good luck with, but this was a higher gravity than I've done before. Other than getting a device to aerate the wort, are there other techniques? I was thinking of passing it through a fine strainer when I put it into the fermentation bucket, that ought to help, right?
2) I didn't take more than the OG and FG readings (though I should have when I dry hopped to check it out). Hope I don't have bottle bombs now! In the past I've always let brews go for 2 weeks before bottling. Would the yeast have stalled then kicked back into gear later?
I transfer my chilled wort to a bottling bucket through a fine mesh strainer, pour a sample, add the yeast and stir.

I trickle the wort out of the spigot down the inside of a carboy so it fans out across the side and aerates. Airlock and I'm looking at krausen within 12 hours.

You could do the same on the side of the bucket and whatever hosing / valve you are using to transfer from the kettle as well.
 
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TropicThunder

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I transfer my chilled wort to a bottling bucket through a fine mesh strainer, pour a sample, add the yeast and stir.

I trickle the wort out of the spigot down the inside of a carboy so it fans out across the side and aerates. Airlock and I'm looking at krausen within 12 hours.

You could do the same on the side of the bucket and whatever hosing / valve you are using to transfer from the kettle as well.
Thanks for the feedback! That's an easy way to do it. I'm looking at strainers over at Amazon - what micron size strainer do you use?
 

Tribe Fan

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Thanks for the feedback! That's an easy way to do it. I'm looking at strainers over at Amazon - what micron size strainer do you use?
Just a wire mesh kitchen strainer from BB&B, basically to catch any big particles from the hops. I pour almost all of it in and let the trub settle after it ferments. You can go any size you want that fits your setup.
 

RM-MN

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According to the manufacturers, dry yeast does not require aeration so your stirring wasn't even necessary. The temperature of the fermentation does matter as the yeast tends to heat up the beer and that can lead to off flavors during the initial fermentation but if too cool the yeast will drop out before completing the job. A bit late for this batch but in future batches, let the beer sit in the 66 degree area (in a tub of water preferentially to keep the temp steady) then after 4 to 7 days, let it warm to the low to middle 70's to help the yeast finish.
 
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TropicThunder

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Just as a follow-up, I cracked a bottle and took another FG reading and it hasn't budged, so the yeast is done.

RM-MN, thanks for the feedback - would agitating the fementor every few days help keep the yeast in suspension? Our basement stays a constant 66 degrees, but it would be tough to regulate temperature anywhere else in the house (it heats up in the afternoon, cools in the evenings, the AC doesn't do a fantastic job).

How do you folks increase temps and keep them constant?
 

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