Fermenting slowed then started back up

[Indyoshi]

So I started a milk stout and dont have temp control...(first home brew) It was a bit warm the first day but then I saw some swamp cooler posts and did that to keep it in the 70 degree range (I am in Galveston and its pretty humid and hot). After doing the swamp cooler the fermentation seemed to slow down. It has been in the primary for 16 days and yesterday I took it out of the swamp cooler as I read that warming it up a little can help the yeast finish up before bottling. I didnt want to pop the bung off the carboy yet and havent taken a gravity reading, but the bubbling stopped (not just the airlock, but the top of the beer was smooth and when looking at the trub there were no bubbles coming off it). the temp is now at 72 degrees and it seems to have gone back into fermentation. The airlock is bubbling again every 8 or so seconds and I can see CO2 coming off the trub on the edge of the carboy. Its even starting to get a layer of krausen again which already fell once. Did I let it get too warm? I dont want to make bottle bombs, so obviously I am not going to bottle just yet since it is active again. If I cool it back down to 68-ish I presume it will slow down and or stop again... should I do that or just let it do its thing with 71 degree ambient temp?

Cant provide much on the yeast... it was a partial extract kit and I dont know what kind of yeast was in it.

ideas?

It smells fantastic BTW... cant wait to try it, but I dont have a problem leaving it in the primary for a month. I have parts on the way for a kegerator and another primary with a Hefe (sencond brew started 3 days later) that Ill probably bottle first... just because even after warming it up a little, it has not started bubbling again and is clearing up quite a bit.

Anyways... is this normal, or at least no cause for major concern?

 

[twistr25]

Typically just disturbing it can cause CO2 to come out of solution and cause more bubbling. Your best bet is to take the gravity reading. My guess is it should be done, but that's the only way to know for sure. For future, you want to get that swamp cooler into the mid 60 range, that'll really help your beers out.

 

[fuzzy2133]

Typically just disturbing it can cause CO2 to come out of solution and cause more bubbling. Your best bet is to take the gravity reading. My guess is it should be done, but that's the only way to know for sure. For future, you want to get that swamp cooler into the mid 60 range, that'll really help your beers out.

+1

If you moved the beer when active fermentation was almost complete (Krausen just fell) some times the yeast gets stirred up and becomes active again. Sounds like you are past that point though.

 

[Indyoshi]

I have read a lot about people fermenting in the mid 60s temp wise. I have always thought most just throw it in a closet, and I sure dont keep my house that temp. No basements on the island that I know of either... I have an old fridge in the garage Ill likely be turning into a fermentation chamber... the LHBS said it wasnt needed unless doing a lager, and they have several carboys just out in the open at the store (not even covered from light). That seemed odd to me after reading to keep light away.

After I took it out of the swamp cooler I wrapped a towel around it and let it sit. Its been without the swamp cooler for a couple days and sitting still. Now that the temp is up, its bubbling again. Thats the odd thing to me. I guess at the lower temp it may not have fully attenuated and warming it up woke the yeast back up? I didnt just shake it and it start bubbling... its been sitting still for quite some time and still going...

As for the Hefe, the White labs Hefe yeast stated 70-75 degrees on the bottle... I know (just from reading) there can be a lot of variation and the higher temps lend to fumal alcohols and off flavors, but why would a beer yeast be marketed with that temp range if it is not optimum?

 

[twistr25]

Warming the fermenter back up will cause the CO2 to offgas even with out disturbing it. Same reason if you leave a Coke out in a warm areaafter opening it, it goes flat faster, the CO2 comes out of solution.

The white labs hefe yeast optimal range is actually 68-72. It's typically better to start on the low end of the yeast range and slowly step up.

Have you tried any of the HBS beer, doesn't sound like it would be too good...

 

[Indyoshi]

I read the white labs was 68-72, but the bottle said 70-75. (after just checking the vial, it says pitch at 70-75 degrees, but does not mention anything about fermenting temps). I did try one beer from the HBS that was a bock... it was kegged and tasted pretty good. No crazy off flavors, but Im just learning to detect more flavor profiles.

When it comes to the stout, Ill prob just leave it in there. Ill primary that for 3-4 weeks total and take a reading at the end. Im spooked about infections, so Im not going to pop the bung until I know its ready. haha. as far as the Hefe. Ill try a reading on that today and maybe bottle sunday or monday if no change occurs. It seems pretty done (no activity, no small bubbles in the beer, yeast cake is at the bottom, starting to clear even after 2 weeks in primary)...

 

[fuzzy2133]

I read the white labs was 68-72, but the bottle said 70-75. (after just checking the vial, it says pitch at 70-75 degrees, but does not mention anything about fermenting temps).

When you get into the pitching rate calculators you see that one vile is not optimal for 5 gallons. My guess is the 70-75 is to get the yeast awake and moving faster to make up for the initial under pitch.

 

[Indyoshi]

Now a few days later it is still bubbling every 30 seconds or so (I know the airlock isn't person a Guage of fermentation, but if new CO2 is being created and expelled, wouldn't that mean the yeast are still at work?) it has now been 18 days since I pitched the yeast and seems to still be going. I'm not worried really because eventually it will have to stop and if I end up getting a hit lower FG then that works for me. Thoughts?

 

[twistr25]

Check the gravity, temp and pressure fluctuations can cause CO2 to off-gas, not necessarily still fermenting. Check the gravity a few days apart and if it doesn't change you are good to go.

 

[Indyoshi]

I'll check SG tonight. Kegerator parts don't get delivered till tomorrow and prob won't keg till Saturday at the soonest... Thanks

 

[twistr25]

Then that's perfect timing for spacing out your gravity tests. My guess is it should well be done, but certainly better safe than sorry.