Fluctuating temperature during fermentation

[cscaudill]

Hello.

Question: Does a continuous fluctuation of +- 1 or 2 degrees (Fahrenheit) have a large impact on fermentation?

Background: I live in a small apartment, so I don't have the room for a chest freezer to control the temperature. When I brew, I place my fermentation vessel (glass carboy) into a large bucket of water, and I place it in my bedroom (out of direct sunlight). I have a thermometer placed in water, and I try to keep that thermometer at the ideal temperature specified in the recipe (mostly ales). To control the temperature, I keep small water bottles in my freezer and I add them into the water throughout the day. I keep my apartment in the low 70s, so this means that if a recipe calls for fermentation at 66 degrees, then I will use these frozen water bottles to try to keep the water at 66 as close as possible. Before I go to sleep, I may throw in a few extra frozen bottles to drop it to 65, because I expect it to raise throughout the night. Additionally, during the day, sometimes it will raise up to 68 if I don't add new ice bottles in time. My fermentation seems to be very active, but can this continuous variation in temperature restrict the fermentation? Aside from a chest freezer, is there a better way that I could be managing the temperature?

Edit: I should mention that this fluctuation of +-1-2 degrees (F) occurs every day throughout the fermentation. It's not just a one time fluctuation. I play the balancing game with the temp every day, in an attempt to keep it at the ideal temp. I've also added a picture of my ultra high-tech fermentation setup, in case it helps illuminate my scenario.

Thank you in advance.

 

[Coookies58]

Ultimately you are doing the best you can. The slight variation you are getting won’t hurt anything too much. Even with a ferm chamber it’s going to rise and fall as the controller kicks on and off.
I might cover the top with a t shirt or something to keep light of it. Even lightbulbs can cause issues. Try to keep it in the dark.

 

[DuncB]

Looks like you are "cool" with your method. Keep going and a tinfoil hat is reusable and keeps the light off the beer.

 

[iamninjabob]

I've been using the same setup during the warmer months, and I've had pretty good success with it. Just be sure to keep the beer in the dark so it doesnt skunk

 

[DuncB]

Don't let the mesh on the temp probe get wet. I did this when using it to test temp of sparge water, the mesh was trapped loosely under the lid of the sparge water heater and so condensation formed and ran down into the probe sheath. This sent the readings haywire. I had to take it apart clean out the stainless steel tube and dry it all then reassemble. Bit fiddly.
I'm sure you are just popping that probe in each time with your system rather than constant monitoring, but warning just in case the cat knocks it etc if you leave it there between readings.

 

[odie]

a couple degrees is nothing. wide and large fluctuations are. yeast has a pretty wide temp range anyway. Not sure why "68" is the magic number for ales but that seems to be most common. Anything mid 60s to low 70s is fine IMO for most beers. Obviously precise control is nice but typical AC setting in most houses is fine.

 

[CascadesBrewer]

Question: Does a continuous fluctuation of +- 1 or 2 degrees (Fahrenheit) have a large impact on fermentation?

What you are doing there seems like a good start at controlling fermentation temps. It is similar to what I have done in the past and likely many others.

I will note that keeping the fermentation temp in that 66F-ish range is more important toward the start of fermentation during the yeast growth and active fermentation stages. As fermentation slows, I find it useful to let the temp rise up a bit to help the yeast finish up. So as you start to see the fermentation slow (often day 3 or 4) you could likely stop adding ice and let the fermenter warm up to room temp. The extra water will help to buffer temp swings.

 

[Alex4mula]

You are doing great. My ales drift +/-2 deg. My lagers +/- 4.5 deg. All come out great. It’s hard to brew to standards with space limitations. Brew on!

 

[DuncB]

Perfection is the enemy of good. Plenty of beer made ( especially ales ) with no temp control in the past. But I try now to control the temperature within my boundaries.
It was so simple when I started, now it's water, pH, temperature, recipe, milling, condenser, whirlpool, filter, oxygenate ( build a starter forgot that), temp control, dry hopping, pressure ferment, kegging,carbonating, bottling, yeast harvest, finings, randallising and a nitro setup so many things for a nearly full glass of water!!
But the product is a damm site better than those extract kits that's for sure.
Just waiting for the beer engine at the moment then it's cask ale learning curve.

 

[Phitz]

Have a Extract kit using 05. Been fermenting 11 days at 60 degrees. Started out strong after 36 hours then airlock activity petered out after 5 days. Just moved to 67 degree closet and she’s rolling again. Will dry hop in a few days and bottle after another week.

 

[DuncB]

Thats cool for an ale is it a pseudo lager / pilsner ferment you are doing? You could let it cool again towards the end of dry hop I suppose.

 

[JimRausch]

cscaudill- I've done exactly what your setup is. 9 years now and over 175 batches. Ales of all types year-round and lagers in the winter. It works. Why? The concept is thermal mass. The amount of water in the bath moderates the temperature swings. I take the temp of the bath 2-4 times daily during fermentation and adjust accordingly with frozen water bottles or an aquarium heater when I need to increase temps. I might also crack open the door to my garage to let in a little cold air to my basement, or move the whole setup a little closer to my furnace if needed.

 

[Phitz]

Thats cool for an ale is it a pseudo lager / pilsner ferment you are doing? You could let it cool again towards the end of dry hop I suppose.

It’s a Citra IPA. Only my second batch. First one I did a Chinook IPA same yeast and left it at 60 degrees for the whole fermentation. Thought i would try bringing the temp up and see what happens. 60 is the low end for 05, but 67 is probably the sweet spot

 

[DuncB]

I tend to bring the temp up a couple of centigrade for a day or two at the end for a diacetyl rest ( taking no chances ), just a habit I learnt with patience.

 

[cscaudill]

Thank you everybody for the responses! I always appreciate the collective support and guidance of the homebrewing community.

 

[ncbrewer]

I use a larger (1 liter) ice bottle and put it in a bubble wrap bag - one with mini air bubbles (sometimes a small bottle or two bottles, depending on the situation). This combination lets the ice melt slower so the temperature swings less than using small bottles. You could try that - it seems to make life easier.

 

[IslandLizard]

I would insulate that whole setup as if the beer depended on it!
Wrap a thick sleeping bag, moving blankets, or such around the whole system.

You'd be surprised how much easier it will be to keep the ferm temps constant, while using far fewer ice bottles.

Once fermentation starts to wrap up, remove the insulation and let her free rise to help condition her out at ambient temps.

Last but not least, keep that carboy covered with something opaque, not only sunlight can be harmful. More so the hoppier the beer.

 

[Bobby_M]

There should be no problem during the main ferment, other than possibly a little more early ester production if the temp rises significantly. Where fluctuation becomes a problem is at the very end of fermentation when the yeast wants to floc out. A couple degrees of a temp dip (which will also occur naturally once the fermentation stops creating its own heat) seems to floc the yeast out and slow down activity enough to leave some Acetaldehyde and/or diacetyl. An aquarium heater in the water bath can help. A general rule of thumb is that you want the last couple days of activity, plus another week should be at 2-3F higher than the average ferment temp.

 

[Culinarytracker]

A degree or two is probably within the delta set by a lot of peoples temp control systems.

 

[CascadesBrewer]

Where fluctuation becomes a problem is at the very end of fermentation when the yeast wants to floc out. A couple degrees of a temp dip (which will also occur naturally once the fermentation stops creating its own heat) seems to floc the yeast out and slow down activity enough to leave some Acetaldehyde and/or diacetyl.

When I finally moved to fermentation temp control about 2 years ago, I expected the main benefit to just be "keep the beer cool during fermentation." Raising up the temp and holding it at the low 70F range to finish out fermentation may have been the biggest improvement in insuring consistent fermentations for my standard ales.

I also like the ability to set-and-forget (vs messing with vents and and my house thermostat, or ice), the ability to cold crash, the ability to brew more styles of beer, and not having the season impact what I can brew.

 

[DuncB]

Agree Cascades and also less worry about constant checking and fiddling.