Author Topic: Two Different Krausens / peaks of activity?  (Read 2673 times)

Offline aparce

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Two Different Krausens / peaks of activity?
« on: October 28, 2012, 08:17:59 AM »
Hello All,
This was my first extract batch where I used a yeast starter, making a Black IPA. I did the calculations to create as appropriate a starter as I could for this 1.075 beer, used a stir plate for 20 hours, put it in the fridge for a day, made the wort exactly as I had my previous beer which have been turning out quite well, decanted the starter, and poured it in. If anything the OG was a bit under the target, more like 1.071.

I saw a very healthy krausen kick up within about 8 hours of the fermentation, it was bubbling away furiously and then about 2 days later started to fall back down. I was a little disappointed that the fermentation was done so quick, thought that was a bad sign. Then about 12 hours later a "cleaner looking" krausen started to rise. I'm almost 4 days into the fermentation now and this newer Krausen is even taller than the first one I saw. I am pretty meticulous about sanitization and cleaning, and cant think of anything that I did differently in this batch aside from the yeast starter that would have infected it. Any ideas on what might be going on?

Offline bigchicken

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Re: Two Different Krausens / peaks of activity?
« Reply #1 on: October 28, 2012, 02:39:55 PM »
I'm no expert on this, but my thought is that simple sugars were consumed right away and now the yeast is working on more complex sugars. Did you use any table sugar?
TJ Cook
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Offline aparce

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Two Different Krausens / peaks of activity?
« Reply #2 on: October 29, 2012, 05:26:03 AM »
Of course, I hadn't thought of that! This also happened to be the first beer I have ever done with a late addition of corn sugar to bump up the gravity. That would make a lot of sense that they would burn through the simple sugars first. Thanks for your help!

Offline a10t2

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Re: Two Different Krausens / peaks of activity?
« Reply #3 on: October 29, 2012, 07:15:17 AM »
Have you checked the gravity? I'd be more inclined to say that this second "krausen" is just CO2 coming out of solution. Has the temperature been steady throughout?
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Offline denny

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Re: Two Different Krausens / peaks of activity?
« Reply #4 on: October 29, 2012, 08:55:02 AM »
Have you checked the gravity? I'd be more inclined to say that this second "krausen" is just CO2 coming out of solution. Has the temperature been steady throughout?

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Offline aparce

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Two Different Krausens / peaks of activity?
« Reply #5 on: October 29, 2012, 02:30:22 PM »
The temperature has been between 65 and 67 F the entire time. Would the primary phase of fermentation be done that quickly? The second krausen didn't actually have the airlock bubbling too much...

Offline a10t2

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Re: Two Different Krausens / peaks of activity?
« Reply #6 on: October 29, 2012, 04:18:53 PM »
Is that 65-67F beer temperature, or air temperature? At high krausen the beer will be around 6-10F above ambient.

If you've been under-pitching in the past, you definitely wouldn't have been seeing fermentation proceed at a "normal" rate. Two days is a little quick for a 1.071 beer, but not crazy, especially if the temperature was high.

Regardless, you'll have to check the gravity to know what's going on.
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Offline aparce

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Re: Two Different Krausens / peaks of activity?
« Reply #7 on: October 29, 2012, 07:48:11 PM »
Hey, you guys were totally right. I just got back from a business trip, "2nd Krausen" was still as it had been but the air lock had almost stopped bubbling. I took a gravity reading of 1.015, transfered it to secondary, thiefed a little bit and it tastes pretty great for this point in the process.

Just for my future knowlege:
a. Is it a problem if the CO2 falls out of suspension (such as mine did)?

b. I'm not sure I trust my stick-on liquid crystal thermometer to accurately tell me what's happening Inside the carboy. Is there a better temperature monitor that I could use inside the frige I converted for brewing and am using a digital thermostate to control?

Thanks for all the help and sorry for the "newbie" questions, your advice has been super helpful!

Offline Mark G

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Re: Two Different Krausens / peaks of activity?
« Reply #8 on: October 30, 2012, 06:49:23 AM »
a. No, this is perfectly normal.

b. Those stick on thermometers are amazingly accurate. You could get a thermowell, etc. but in my opinion, it's not really worth it. I would suggest taping the probe from your temp controller to the outside of the fermenter under some sort of insulation so it controls the beer temp, not just the ambient air.
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