Slow / stuck double IPA fermentation

Hi All,

I've had really bad luck with a DIPA fermentation and I can't wrap my head around what could have gone wrong. The recipe is basically a Pliny clone. My original gravity was 1.082 and I pitched about 400 ml of fresh slurry from a previous primary into the new wort (about 6 gallons). Fermentation started within about 10 hours and was vigorous by about 18 hours. So everything looked good, and I thought I could expect decent attenuation. Tonight I took a reading thinking that primary was about done but to my intense dismay the reading was 1.038. Any ideas why this could be? It's still fermenting slowly, but since I'm 11 days in I would have expected it to be finished.

Thanks,
Sean

What was your mash temp? Fermentation temp? Did you include lots of crystal malts?

Mash temp? Method of oxygenation? I've heard some yeast lab folks say oxygenation is even more critical when re-pitching.

oxygen? yeast nutrient? mash temp? also, you have no idea what your pitch rate is when you dump onto a cake....

Piratwolf said:

What was your mash temp? Fermentation temp? Did you include lots of crystal malts?

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The mash temp was 66 C (150.8 F). I ferment at 19 C (around 66 F) then bumped it to 20 C after 4 days and 21 C on the 5th day.

For malt bill, not much crystal. 86% Canadian 2 Row, 6.1% Dextros, 3.9% Cara-Pils, 2.8% Crystal 10L and 1.3% Crystal 40L.

I use a small oxygen tank with a stone attached to a hose... It's hard for me to figure out how much oxygen is actually getting released. That's one part of my system I'd like to work on. But I did see bubbles rising to the surface and I kept it in there for about 2 minutes.

Did you make a starter with the slurry? How old was the yeast and how was it stored?

Kaz said:

Did you make a starter with the slurry? How old was the yeast and how was it stored?

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I didn't make a starter because it was just coming off the tail end of an APA primary (basically a 5.5 gallon starter). So I would have thought that if anything I was over-pitching by wide margin.

I had made a ~ 1 liter starter for the APA and it fermented nicely, from 1.50 to 1.013 (67 C mash temp).

From everything I read from you, you did everything right.

Have you checked your thermometer to confirm mash temps.

Only other thing I can think of; is your fermentation temp. Are the temps you are quoting the wort/beer temp, or air temps. It's a long-shot, but fermenters take on the temperature of the floor rather than the air (better thermal transfer), and you could have a lower wort temp than you think. It's probably not the case, but it would explain how the yeast would slow or give up half way through.

Try moving the fermenter to a warmer location to see if you get any more activity ..... what do you have to lose!

Calder said:

From everything I read from you, you did everything right.

Have you checked your thermometer to confirm mash temps.

Only other thing I can think of; is your fermentation temp. Are the temps you are quoting the wort/beer temp, or air temps. It's a long-shot, but fermenters take on the temperature of the floor rather than the air (better thermal transfer), and you could have a lower wort temp than you think. It's probably not the case, but it would explain how the yeast would slow or give up half way through.

Try moving the fermenter to a warmer location to see if you get any more activity ..... what do you have to lose!

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Yeah, like I said, I really can't wrap my head around it. Maybe there was something "unhappy" about the yeast from the previous batch, but not sure what. Maybe high amounts of hop components (lots of late hopped simcoe in that one)?

My temp is regulated with a dual stage controller with the probe inserted into a metal holder immersed in the wort/beer... so those temps are quite accurate.

All in all, very frustrating, especially since a DIPA is a relatively expensive recipe to brew (lots of pricey American hops).

Anyway, I guess the question now is what to do with it. Champagne yeast? It's still fermenting for the moment, but I'm not sure how much longer it will keep up. I guess I could increase the temp another degree celsius? I'm using WLP001 here.

Thanks to everyone for your help.
Sean

I would let it go and see what happends. If you still have decent activity, no reason to keep taking readings. BTW, what yeast strain are you using?

MaynardX said:

I would let it go and see what happends. If you still have decent activity, no reason to keep taking readings. BTW, what yeast strain are you using?

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Yes, I guess I'll wait a bit and see. I'm using WLP001. I was hoping for at least 80% ADF given the sugar in the malt bill...

Calder said:

From everything I read from you, you did everything right.

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Agreed. I can see why you're frustrated! I've had some luck getting the last few points to finish by taking my carboy to a warmer closet and letting it rise to 70 or so. It may help, although your batch has more than a "few points"!

Hi everyone,
Just wanted to update this thread in case anyone is ever stuck (pun intended) in a similar situation to this. A day or so after I last posted I added some dry yeast in hopes that it would get the brew fermenting more vigorously again. It didn't have any effect but the brew did continue to ferment with about the same level of activity as I observed before. I kept waiting it out, taking occasional readings and the fermentation continued the whole time, albeit slowly. Anyway, just took a reading and it's down to 1.016! That's exactly where I wanted it. I just racked it and added the requisite ton of dry hops. It tastes real good as it is, can't wait to taste the final result.

So, while my fermentation wasn't ideal, the end result is nothing to complain about.

Cheers,
Sean

Good news! Thanks for reporting on the outcome!