repeated problem with fermentation

[dand11587]

Hey guys, i have been lurking on here for a couple months soaking up all the great information around here. Thanks for all of it!

But i've been having one problem that i can't solve. For my last 5 or so batches, my fermentation stops at around 1.030. This gravity is consistent despite variations in starting gravity (1.050 up to 1.080).

I thought it might be due to temperature drops during the night. I live in a drafty apartment. But I kept a close eye on the temperature for the past few days on this last batch and the problem has returned!

I am using nottingham yeast for all of these batches. fermentation temps have been between 60 and 63, and as i said earlier, sometimes ambient temperature drops to mid fifties during the night.

I don't know what else to check. I have been consistent in my brewing methods and I haven't had this problem in the past when I was using safale 05. I have read about how mash temps affect fermentability, and my mash temperatures range from about 154 to 158. Does mash temp really have that much affect on fermentability?

This is really bothering me. What do you think the issue is?

Dan

 

[Reno_eNVy]

Low 60's isn't that bad, it'll just take a bit longer. That could be the issue, or it could be the change in temperature. If it's 1 or 2 degrees... no biggie. More, then you may have a problem. So, maybe you should just give the yeasties more time.

If you want to solve the changing temperature problem, put the fermentor in a water bath. Water is far less subject to adjusts in temperature than air is.

 

[Stef1966]

You mentioned the temps dropping in the mid 50's during the night, IMO that could be a serious issue knowing definite yeast strains will be at ease in a definite temperature range, the yeast might have gone partially dormant withing those temps.

Also, have you tried other yeast strains yet in the same environment?
Different yeasts have different attenuation rates and temp ranges, those are critical factors, but stopping dead at .030 definitely seems a bit off to me.

about your .030 FG did you take a SG and then another something like 3 days after confirming it really had stopped right there?

 

[ericm]

some things:

check your hydrometer (does it read 1.000 in water (at 60 F)?) While you're at it, it's a good idea to check the thermometer you're using for your mash. It should read 32 in a glass of ice water, and 212 in a pot of boiling water.
mash temp definitley affects fermentability - 158 is pretty high as well, and would be expected to leave a significant amount of unfermentables.

 

[dand11587]

i calibrated my thermometer, and it said boiling water is 206 fahrenheit. that explains a lot.

i looked at my records of my brews, and all of the batches that had lower mash temps (according to this thermo) in the high 140s or low 150s fully fermented, and all that recorded in the mid 150s stalled at 1.030ish.

Now i know that i must correct my temps by -6 and i should be back to making great beer!

thanks for the help, hopefully i'll have enough knowledge to start helping others out.

 

[leboeuf]

Before you harp on your thermometer too much, the altitude you live at could easily cause a 6 degree drop in boiling temp. I live around 6000 ft and water boils just above 200 degress F. So if you also live at altitude you may not want to calibrate based on the boiling temp of water...

 

[ericm]

that's a good point about the boiling point of water being altitude dependent! if you know your altitude, you can calculate what the boiling point should be, and use that to calibrate (edit: here's an online boiling point calculator: Water Altitude Boiling Point Calculator )

but based on you looking back at your notes and seeing that the lower mash temps fully attenuated and the higher temps stalled, it does sound like that's the issue.

 

[IrregularPulse]

cool, My boiling point today is 210. Good to know. i would have just assumed my thermometer was off because of figuring I am in no real altitude being in Ohio.

 

[Denny]

I have read about how mash temps affect fermentability, and my mash temperatures range from about 154 to 158. Does mash temp really have that much affect on fermentability?

This is really bothering me. What do you think the issue is?

Dan

Yes, it does, and the range you're in will produce a wort high in unfermentables. Try mashing at 148-150 and see what happens. And as others have said, check your thermometer. I don't find the boiling/freezing test very effective since I've had thermometers that are on at the extremes but off at mash temp. I calibrate my brewing thermometer at 150F.

 

[BuzzCraft]

For my last 5 or so batches, my fermentation stops at around 1.030. This gravity is consistent despite variations in starting gravity (1.050 up to 1.080).

Dan

just to confirm that you're checking your final gravities with a hydrometer and not a refractometer?

 

[MacBruver]

Since you've been using the same yeast for every batch- did you buy it all at once, or are you getting it from the same source? Have you tried doing a "fast ferment" test?

 

[drayman86]

Three recommendations to help avoid a stuck fermentation:

1. Aerate the wort thoroughly.
2. Aerate the wort thoroughly.
3. Aerate the wort thoroughly.

Sloshing around in the carboy is a minimum. Using an active system like a strong aquarium air pump or small disposable oxygen tank should be come a regular part of your brew sessions.

 

[ericm]

Yes, it does, and the range you're in will produce a wort high in unfermentables. Try mashing at 148-150 and see what happens. And as others have said, check your thermometer. I don't find the boiling/freezing test very effective since I've had thermometers that are on at the extremes but off at mash temp. I calibrate my brewing thermometer at 150F.

this is also a good point - thermometer inaccuracies aren't necessarily linear; so just because it's on or off at boiling or freezer doesn't mean it's on or off at mash temps. the caveat is that to calibrate at mash temps you need a reliable standard (ie. an nist calibrated lab thermometer or something long those lines). without that, checking that your thermometer is on at both extremes is a reasonable second best.

 

[MacBruver]

this is also a good point - thermometer inaccuracies aren't necessarily linear; so just because it's on or off at boiling or freezer doesn't mean it's on or off at mash temps. the caveat is that to calibrate at mash temps you need a reliable standard (ie. an nist calibrated lab thermometer or something long those lines). without that, checking that your thermometer is on at both extremes is a reasonable second best.

Calibrating a fluid thermometer with the boiling/freezing method works well. It's very hard for those to not be linear, unless there is a defect in the tube of the thermometer.

A much cheaper way of eliminating error than that is to use multiple thermometers, of different types. I have a digital, dial, and liquid thermometer, and I've tested all three of them together. The dial one reads a bit high, which doesn't surprise me too much. It's highly unlikely that they would all be off in the same direction, by the same amount.
If you want a calibrated one (with certificate) though, they're available for about $100:

ThermoWorks – Super-Fast Hi-Accuracy Thermapen. We are temperature experts thermometer thermapen haccp probe calibration fast quick accurate measurement

 

[dand11587]

im in chicago area, so i guess water boils around 210 degrees, still quite a bit off, especially considering how important you guys say hitting your mash temps is.

I will try a batch tomorrow at a lower temp and see how it goes.

Is it advisable to just rack one of my batches that stuck at 1.030 and pour the new wort right on that cake? or should I start with new yeast? If the mash temp is the problem and not the yeast, then it should be fine, right?

 

[BuzzCraft]

If the mash temp is the problem and not the yeast, then it should be fine, right?

yes, should be fine...

 

[mkade]

How much yeast are you pitching?

 

[Hammy71]

Three recommendations to help avoid a stuck fermentation:

1. Aerate the wort thoroughly.
2. Aerate the wort thoroughly.
3. Aerate the wort thoroughly.

Sloshing around in the carboy is a minimum. Using an active system like a strong aquarium air pump or small disposable oxygen tank should be come a regular part of your brew sessions.

My last two brews have ended in the 30's as well. My conclusion is the same as Drayman's.... I never worried to much about aeration....just shook the carboy for a couple of minutes and everything went fine. But....my last two brews called for 90 min boils. My stuck fermentations have to come from that fact...(all 60 min boils have done perfect everytime.). A 90 min boil must really de-oxegenate the wort. (Makes logical sense....). So therefore I'm looking into ways to aerate my wort. I purchased a simple whip for my cordless drill for todays brew...and I'm planning on ordering a oxygen set up this weekend on line...(my lbs didn't carry 'em). Having reached this conclusion... I now have two beers sitting in carboys that are pretty useless. I'm going to attempt to use Evan's procedure to get the brews started again on the yeast cake for the beer I'm brewing today... Short of that....what'll I do? I don't dare try to oxygenate the brews now.....But my question to the original post is.... Are you aerating properly?