Opening carboy....worth the risk?

So I was just curious to find out everyones opinions on opening the carboy during fermentation. Im just really curious to find out what the temp inside the fermenter is. I am using a swamp cooler with the water level up to the level of the beer. I have seen many different opinions on the difference in temp from the beer and the swamp cooler water. I have seen people say anything from 1 degree to 10 degrees. I guess I just want to find out for myself.

As long as you use good sanitation techniques, there should be no more risk than taking a sample for a gravity reading, that is little to none. IMHO

Is it a carboy or a fermentation bucket. To take the top off a carboy carries less risk than taking the top off a bucket. Either way you can do it. I would recommend getting a wine theif and taking a sample. You can then take the temperature, the gravity and best of all a taste.

+1 Doug. If you sanitize everything, the risk is pretty close to zero. You'll always have non-zero risk any time you open the fermenter, but as long as it's for a good cause -- e.g. taking a temperature reading -- it's fine.

I wouldn't worry about it BUT truly if you want to know the temp of the fermenter, then you can tape your temp probe to the class and after awhile it will give the the temp inside. Especially since it's in a swamp cooler, the glass and the beer are going to be the same temp if you are above the water line.

I like those stick on thermometers my self, I guess one of those would work too, above the waterline and below top of the beer.

I'm with D0ug. I use the stick on thermometers and they do the trick.. Then you don't have to worry about sanitizing the thermometer or anything... Instant gratification.

Scut Monkey....It is in a carboy

Revvy.....Would it make a difference if I am using a plastic carboy?

I guess this brings up another question. Will it make a significant difference in cooling if I lower the water level to a couple inches below the beer level to accomodate a stick on thermometer? Im assuming they wont work or will be ruined if they are submerged.

I"ve read that stick on thermometers can be ruined if they are soaked in water.
I dont have it but I"m thinking to buy one of them soon.

Since I got my 1st batch fermenting (brewed 2 days ago) and I have read plenty "fermentation temperature" threads that say that temperature inside of carboy can be 5-10 degrees warmer than room temperature, I am trying to figure what temperature is in carboy.

I have digital thermometer like this:
http://cgi.ebay.com/Digital-Cooking...172?pt=LH_DefaultDomain_0&hash=item2a104c9e64

What is most accurate method to measure temp inside?
Maybe to fill some water around carboy and as Revvy said, to tape temp probe to the glass?
Anyone tried this method?

If it's a glass carboy taking a sample with a wine theif is pretty straight forward. The small opening will help to limit how much dust with bacteria and mold can fall into the beer. Most brewers take sample during fermentation.

Stick on thermos will give you a rough estimate of the temperature. I never really trusted the accuracy and with a swamp cooler the water ruined one of mine. They work though and are a good solution.

In a water bath that almost covers the level of the beer, the water and the beer will be very close to the same temperature. I float a floating thermometer in the water bath.

I've been playing around with my laser thermometer (remember, only measures surface temperature) and I can see the effects of the heat of fermentation pretty clearly. The surfaces in my kitchen are about 68F. Every surface within about 8-10 inches of either of my fermenters is 69F. One fermenter has a beer that has been in primary for 16 days: it reads 70.5F. The other fermenter was started up on Sunday: it reads almost 72F. They are both glass carboys, not in a water bath.

FWIW. That, I think, would be consistent with the most common estimates I hear, which is +5F (if the internal temp is a degree or two higher than the surface temp, that would be exactly a 5F differential). YMMV, and of course every fermentation is different.

I use a floating thermometer in the water bath as well. I just want to find out what kind of temp difference there is.....have you guys found that it is 1-2 degrees?

JonBoy47 said:

I use a floating thermometer in the water bath as well. I just want to find out what kind of temp difference there is.....have you guys found that it is 1-2 degrees?

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It will completely depend on how active the fermentaion is. To give an exact number or a range would be an inaccurate guess.

The time I am most concerned with is during the heavy fermentation (first 3-5 days-ish). I want to figure out what temp the water needs to be to keep the beer in the 68 degree range. I guess the only way to figure that out will be to pull the stopper and get myself a temp.

I just got measurement from water bath: in room temperature of 64 F water was 70 F.
For the record, level of water was just above half of beer level, so I assume that the temp. could bee couple degrees higher.

Yooper said:

In a water bath that almost covers the level of the beer, the water and the beer will be very close to the same temperature. I float a floating thermometer in the water bath.

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+1

The fermenter is a lousy insulator and the beer and water in your swamp cooler will be the same.

Scut_Monkey said:

Is it a carboy or a fermentation bucket. To take the top off a carboy carries less risk than taking the top off a bucket.

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I drill out my bucket lids with a hole I can put a standard carboy stopper in for the airlock. Only one size of stopper to keep around, plus I can fit a wine thief through the hole without taking the lid off. I can even get my autosiphon in there if I want and not take the lid off until after the transfer.

beerkrump said:

+1

The fermenter is a lousy insulator and the beer and water in your swamp cooler will be the same.

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Except fermentation is an exothermic reaction. The beer can be warmer than the water.

diS said:

I"ve read that stick on thermometers can be ruined if they are soaked in water.
I dont have it but I"m thinking to buy one of them soon.

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True story. I just ruined one last batch because I had my fermenter in a cold water bath.

ChshreCat said:

I drill out my bucket lids with a hole I can put a standard carboy stopper in for the airlock. Only one size of stopper to keep around, plus I can fit a wine thief through the hole without taking the lid off. I can even get my autosiphon in there if I want and not take the lid off until after the transfer.

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That's a good idea. I'll have to keep that in mind if I start using buckets again. Even taking the lid of buckets can be a chore sometimes.

ChshreCat said:

Except fermentation is an exothermic reaction. The beer can be warmer than the water.

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No, it can't. Sure, fermentation is exothermic, but in a water bath it's basically 5 gallons of beer (inside the fermenter) and, say, 5 gallons of water around it. That's 10 gallons of liquid which will take a LONG time to change temperature, and the beer and the water will be the same temperature, or very very close (within 1 degree). If you add a frozen water bottle to the water bath, and the water changes temperature, so will the beer.

Yooper said:

No, it can't. Sure, fermentation is exothermic, but in a water bath it's basically 5 gallons of beer (inside the fermenter) and, say, 5 gallons of water around it. That's 10 gallons of liquid which will take a LONG time to change temperature, and the beer and the water will be the same temperature, or very very close (within 1 degree). If you add a frozen water bottle to the water bath, and the water changes temperature, so will the beer.

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I gotta argue on this one. I've measured a temp difference between my water bath and my beer. In the first stages of fermentation, it doesn't that long for the yeast to generate enough heat to warm the beer up. Without agitation of the beer and the water outside, it takes good time for heat to work it's way through the wall of the fermenter.

ChshreCat said:

I gotta argue on this one. I've measured a temp difference between my water bath and my beer. In the first stages of fermentation, it doesn't that long for the yeast to generate enough heat to warm the beer up. Without agitation of the beer and the water outside, it takes good time for heat to work it's way through the wall of the fermenter.

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I think Yooper was talking about the steady state condition, not the transient at the start of fermentation.

Do you guys think if I made some kind of thermowell and put in a 12" glass thermometer I would get an accurate reading?

K.I.S.S.

take a sample, take a direct reading, or take a reading from the bath.

Just sayin'...
when ever I try to get too creative or over think it, I usually blow it.