Fermentation Water Bath Fiasco

[chato]

I've been trying to rid my beers of twang so I decided to try a water bath. My thermometer read 70 F when I turned off the wort chiller, so I went ahead and oxygenated and pitched my yeast. I then put the carboy into a water bath that came up about 1/2 way to the top of the carboy, filled with 64-65 degree water.

What happened was a little odd, but I suppose I should have anticipated this. The fermometer attached to the fermentor sits just above the water level. After a couple hours it was reading in the high 70s. There was minimal yeast activity. The whole purpose of the water bath was to keep the beer below 70, so I dumped a bunch of frozen ice bottles into the water and went to bed, hoping for the best. This morning the fermometer was reading 66, while the water was 55. So I pulled the carboy out of the water bath. The beer had striated, with cloudy (yeasty?) beer on top and clear (probably floculated) beer below. It must have developed a thermal inversion with the yeast dropping out of the bottom half of the fermenter, and the top 1/2 fermenting normally.

The overall yeast activity was low given the time since pitching. I decided to give the bottom a stir to get the yeast back into suspension and even out the temps. As soon as I stirred it up, the krausen went from about 1/2 inch to blowing out the top within about 15 seconds. It was amazing! That settled down after a couple minutes and now its sitting at 66 and bubbling away.

So, my questions:

What happened when I stirred the two layers together that would cause the sudden explosion of activity?
Should the water bath cover all the way up to the level of the wort in the carboy?
Should I expect this batch to be ruined (twangy) due to this fiasco?

 

[johngaltsmotor]

Just like cold finished beer, cold fermenting beer can hold more CO2 dissolved. When you stirred it and mixed the two temperatures you raised the temp of the bottom half. This caused it to be unable to keep all of the CO2 dissolved so it released the excess based on its new warmer temperature.

 

[Foosier]

I believe that when you stirred the fermenter you released the carbon dioxide from the yeast. This is like hitting the carboy/bucket and getting bubbles in the airlock.

I would probably keep the water at about the same level as the wort. I think it actually needs to be level or just below to keep the fermenter from floating on you. This will give you thermal mass and prevent striation.

Batch should not be ruined. You are controlling temps. It may not have been perfect, but you are doing more than you have done before.

 

[mtnagel]

That's odd. I use a water bath to control fermentation temperatures and haven't experienced anything like that. I put my 5 gal bucket in a small rubbermaid tote filled up to about the 3 gallon mark on the bucket (so it isn't up to the level of the wort). I have a thermometer in the water bath and I've never seen it rise like that during fermentation. In fact, most of the year I have to add heat to the water bath to keep it from being too low in my basement (I use an aquarium heater). I have a stick on thermometer on the bucket and the wort temperature always reads very close to what the water bath reads and I have even opened it up during active fermentation and measured the wort temperature and it was within 1 degree of the water bath temp.

I do use a homemade stir plate on the side of the tote to keep the water circulating in the water bath so I'm sure that helps.

 

[chato]

Just like cold finished beer, cold fermenting beer can hold more CO2 dissolved. When you stirred it and mixed the two temperatures you raised the temp of the bottom half. This caused it to be unable to keep all of the CO2 dissolved so it released the excess based on its new warmer temperature.

That makes sense, the CO2 in solution in the cold layer was released when it warmed up from the stirring.

I believe that when you stirred the fermenter you released the carbon dioxide from the yeast. This is like hitting the carboy/bucket and getting bubbles in the airlock.

I would probably keep the water at about the same level as the wort. I think it actually needs to be level or just below to keep the fermenter from floating on you. This will give you thermal mass and prevent striation.

Batch should not be ruined. You are controlling temps. It may not have been perfect, but you are doing more than you have done before.

Thanks for this. This hobby is so nerve wracking. My heart starts to race when I realize I might have just screwed up and I might have to drain pour $50 worth of ingredients, or drink the whole batch myself because it sucks. You just never know what you're going to get until the day you pop that first bottle.

 

[BikeAndBrew]

As you brew more and get comfortable with your process, that nerve wracking feeling will go away. I used to be the exact same way, constantly worrying about this and that. Now, after brew day I just stick the fermenter in the fridge and forget about it for 2 weeks then keg it. Always turns out just fine. You'll get there.

Also, what are you brewing that costs $50 in ingredients??

 

[johngaltsmotor]

Never pitch it until you carbonate it and test it. I had a batch get infected that's not great, but it's still drinkable (especially as a mixer with a stronger brew). Granted, it might be a waste of time, but I'd rather waste a few hours and verify it was DOA than toss it early and wonder how it might have ended up.

 

[chato]

As you brew more and get comfortable with your process, that nerve wracking feeling will go away. I used to be the exact same way, constantly worrying about this and that. Now, after brew day I just stick the fermenter in the fridge and forget about it for 2 weeks then keg it. Always turns out just fine. You'll get there.

Also, what are you brewing that costs $50 in ingredients??

IPA, Double IPA, Robust Porter, etc. Mostly big hoppy beers that require 2 yeast packs. A lot of my batches have been in the $50-60 range. This particular one wasn't as costly because it's smaller (1.061), I finally bought bulk hops, and I cultured the yeast from cans of Heady Topper. I also don't have a mill so I pay a lot for grain.

 

[BikeAndBrew]

Awesome, sounds like you're well on your way. Saving yeast is definitely a way to save some serious dough. I started washing and reusing yeast and it's saved me a ton.


Sent from my iPhone using Home Brew

 

[MindenMan]

Just curious, what are you paying for grain a pound? I have been reusing yeast for over a year now. I make a starter, pour in the whole "new" yeast container, wait until it is going strong, split it, and put half in the fridge, and build the remaining half to pitch when ready. That way, I always use "new" yeast because I (having learned the hard way) over used one original batch of trub/yeast too many generations, and got awful mutant yeast. Hey, $8.00+ in savings every batch, allows me to brew more often, and keep my grain bills right at $20.0 or less, of course I am brewing a "big" beer, and need more grain.

 

[pmoneyismyfriend]

Forgive me if I missed this, are you doing extract or all grain? I've yet to experience twang in all grain so my assumption is you are doing extract. My experience is, if you are not doing a full volume boil and adding water to your fermentor, you are going to get twang. I was doing all grain for a long time, but this winter wanted to cut down my time spent on the brew, so I've been doing extract brews, full volume boil. The beers are turning out great and I cut my time way down. Last Sunday I did 2 brews in less time than it takes to do one all grain. Get a larger brew kettle and a kick ass burner.

 

[chato]

Just curious, what are you paying for grain a pound? .

My last two batches I got grain from the LHBS, which sells all grains at $1.89 a pound and they mill for free. Before that, I was buying from Morebeer.com and their prices for milled grain are a little on the high side, but if your order exceeds $60, then shipping is free.

 

[chato]

Forgive me if I missed this, are you doing extract or all grain?

No, I do all-grain, using a weird sort of BIAB system. I heard about a half-dozen possible causes of twang, including extract. For this batch, I'm trying to eliminate them all. Temperature seemed to be the prime suspect.