Is my imperial IPA fermentation stuck?

I'm an experienced homebrewer, but pretty new to brewing bigger beers. I mashed my IIPA at about 150F and used white labs california ale to ferment. I made a starter of about 600mL. I used this method.

I'm fermenting at 67+/-2 deg F. About 15% of the fermentables is table sugar.

The OG of the wort was 1.080 on 11JAN14.

I measured it at 1.038 on 29JAN14.

I measured today (2FEB14) at 1.036.

Is it normal to ferment this slowly after 3 weeks? Am I just being impatient?

I am considering making a 3 gallon batch of pale ale this weekend to just get a yeast cake that I can transfer the IIPA onto if the gravity doesn't move. Would that be a good move?

Do I just need to make a bigger starter next time?

I had this same problem with S-05 and a similar OG IPA (pitched onto a S-05 yeast cake). I warmed it up, but it didnt seem to do anything. Ended up pitching champagne yeast and my beer went from stuck at about 1.028 to about 1.018 which i was happy with. Have it on tap now and is one of the best beers I've ever made.

My $.02. Give it a couple more days, maybe put it in a warmer spot of the house. If nothing happens, last resort, try champagne yeast.

danbrewtan said:

Do I just need to make a bigger starter next time?

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600ml is way too small for a beer that big especially if you didn't use a stir plate. Would still be too small even with a stir plate.

danbrewtan said:

Is it normal to ferment this slowly after 3 weeks? Am I just being impatient?

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Normal? Depends on what your definition of normal is. For example, I just kegged my IIPA after 14 days from brew date. OG was 1.081 and hit a FG of 1.009 after 7 days, so for me it would raise a red flag and I would deem it as not normal. I don't have my notes in front of me but I pitched over 300 billion cells if I can remember correctly. Pretty sure you weren't close to that with a 600ml starter and it is probably a big cause for your stalled fermentation.



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Your starter was too small for this batch which could be the problem. You could try getting a couple of dry packets from the LHBS of US-05 rehydrate and pitch to get things moving along. A pale ale where you used the cake after it was done isn't a bad idea either.

I agree with the others that heating it up a bit might help the fermentation start again. Like maybe to the low 70's.

You may have needed more yeast cells to pitch. The starter method referenced is missing some information. This method doesn't take into account the number of viable yeasts you have based on the yeasts production date. Doesn't take into account the estimated OG of the beer being brewed and therefore the number of yeast cells needed. Doesn't recommend a low OG starter (1.020) for very old yeast and then a normal (1.040) step up starter.

Brewers Friend has a starter calculator which does account for the variables. The BF calculator is much like the missing Yeastcalc and allows you to change options according to the beer being brewed.

Are you using a refractometer?

Thanks for all the pointers. Will definitely pay closer attention to my starter size next time.

I'll bring the temperature up to 72 today (I use a deep freezer / Johnson controller) to see if that gets anything going.

And yes, I am using a refractometer. Curious as to why you ask.


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danbrewtan said:

And yes, I am using a refractometer. Curious as to why you ask.

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Raw refractometer readings are totally inaccurate if alcohol is present. Check it with a hydrometer.

Ah, it is my reading. The quick and dirty conversion to correct for alcohol present says it's done. Will double check with hydrometer tonight.

Woot! This also means my other "stuck" beer (that I repitched...) is done too.


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Ah yeah good call with the refractometer question. It's quite possible it's done. You did under pitch this beer but it still can ferment out correctly. The reason to make starters with the correct pitching rate is to get a more consistent fermentations, consistent attenuation, faster starts, and many more reasons...

^ Like drinking the fruits of labour sooner?:rockin:

For anyone that cares, I measured the FG with a hydrometer when I got home and it was 1.008. Done! And now it's bottled. Can't wait to try this one...