Advice On A Stalled All Grain Fermentation

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David Woods

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As I am still very new to A/G brewing I could use a bit of advice.

I brewed an A/G Amber Ale last week and followed the recipe exactly. I hit the correct mash temp etc and the brew seemed to go well. The initial gravity was a bit lower than the recipe at 1040 instead of 1042.

So into the temp controlled fridge and in kicked off about 16 hours later. The fridge temp has been bang on 21c as recommended. Fairly vigorous activity for a couple of days and then it seems to have slowed to a stop. The Tilt shows over two days it had dropped to 1014 which it has stayed for three days now. I planned on leaving in the fridge for 2 weeks anyway but could this have finished already?, this would mean a 3.1% beer - not good.

Could it have fermented and finished that quickly - not had any of my brews finish that quickly before. Has it stalled? if so what should I do. It has been in the fermenter for 6 days now.

So have I shown too much impatience - is it likely to continue to drop? The expected FG is 1008.5. I used Lallemand BRY 97 which I have not used before but came with the recipe kit.

As I am new to this I was wondering how to check the mash has completed properly - any tips? I know about using iodene but didn't do that here. I even let the 60 min mash go on a bit and then did a whirlpool/hopstand for 15 mins so it had plenty of time to convert. If anything the sparge may have been a little cooler than I would have liked but the recipe didn't specify a temp - I sparged at about 65c and as I was pretty close to the expected OG I wasn't concerned.

I am using a Brew Monk AIO

Any advice would be great - I will be leaving it for a while yet anyway. I still have a lot of learning to do!

Thanks
 
Last edited:
Bet it's fine. Whilst I don't have a tilt I don't find my ispindel very accurate below .020 . If you leave it the full two week as planned it will have finished and will probably be closer to target than reported.

You could always use a hydrometer on a sample.
 
Thanks for the reply - yes I will do a hydro reading but was going to wait a bit longer - I was wondering if it had stalled maybe there was something to do now.

As you say I will give it time.
Cheers
 
As I am still very new to A/G brewing I could use a bit of advice.

I brewed an A/G Amber Ale last week and followed the recipe exactly. I hit the correct mash temp etc and the brew seemed to go well. The initial gravity was a bit lower than the recipe at 1040 instead of 1042.

So into the temp controlled fridge and in kicked off about 16 hours later. The fridge temp has been bang on 21c as recommended. Fairly vigorous activity for a couple of days and then it seems to have slowed to a stop. The Tilt shows over two days it had dropped to 1014 which it has stayed for three days now. I planned on leaving in the fridge for 2 weeks anyway but could this have finished already?, this would mean a 3.1% beer - not good.

Could it have fermented and finished that quickly - not had any of my brews finish that quickly before. Has it stalled? if so what should I do. It has been in the fermenter for 6 days now.

So have I shown too much impatience - is it likely to continue to drop? The expected FG is 1008.5. I used Lallemand BRY 97 which I have not used before but came with the recipe kit.

As I am new to this I was wondering how to check the mash has completed properly - any tips? I know about using iodene but didn't do that here. I even let the 60 min mash go on a bit and then did a whirlpool/hopstand for 15 mins so it had plenty of time to convert. If anything the sparge may have been a little cooler than I would have liked but the recipe didn't specify a temp - I sparged at about 65c and as I was pretty close to the expected OG I wasn't concerned.

I am using a Brew Monk AIO

Any advice would be great - I will be leaving it for a while yet anyway. I still have a lot of learning to do!

Thanks
You are controlling the fridge temperature, it is concerning when you say, 'the temperature of the fridge' where is the probe located? Do you have a thermowell on your fermenter? Is the probe stuck on the outside of the fermenter or is that the ambient temperature inside the fridge?
If the probe is on the outside of the fermenter outside of the fermenter then it is always better to drop the set temperature of the controller by a couple of degrees less (21C to 19C) to make up for the exothermal energy produced by the fermenting yeast. If that 21C is the ambient temperature of the fridge then the temperature inside the fermenter can even go as high as 7 or 8C higher than ambient.
As for the SG reading, I would prefer to take a sample, de-gas it, and take a reading while adjusting for temperature. Just to make sure the Tilt isn't throwing you a curve ball.
Provided you maintained the mash temperature for the duration of the mash you could be certain the mash was complete, I prefer to stir the mash regularly for 20 to thirty minutes to break up the hot and cold spots that occur especially in a thicker mash.
The cooler temperature of the sparge water wouldn't have much effect.
 
Floating hydrometers (tilt, pill, ispindel) can never be accurate at the end of fermentation as you get yeast clinging to the pill which will throw the reading off.

Just use them as a guide to when fermentation is done,, then take a hydrometer reading as mentioned above. It'll probably be the gravity you expect.
 
You are controlling the fridge temperature, it is concerning when you say, 'the temperature of the fridge' where is the probe located? Do you have a thermowell on your fermenter? Is the probe stuck on the outside of the fermenter or is that the ambient temperature inside the fridge?
If the probe is on the outside of the fermenter outside of the fermenter then it is always better to drop the set temperature of the controller by a couple of degrees less (21C to 19C) to make up for the exothermal energy produced by the fermenting yeast. If that 21C is the ambient temperature of the fridge then the temperature inside the fermenter can even go as high as 7 or 8C higher than ambient.
As for the SG reading, I would prefer to take a sample, de-gas it, and take a reading while adjusting for temperature. Just to make sure the Tilt isn't throwing you a curve ball.
Provided you maintained the mash temperature for the duration of the mash you could be certain the mash was complete, I prefer to stir the mash regularly for 20 to thirty minutes to break up the hot and cold spots that occur especially in a thicker mash.
The cooler temperature of the sparge water wouldn't have much effect.
Thanks for detailed info - very helpful. I have the probe from an STC1000 fixed to the side of the fermenter with some insulation over it so hopefully the temp is from the wort rather than the ambient temp. The STC also controls a small heater inside the fridge . the temp has kept within 1/2 deg pretty much all the time and the temp readout from the Tilt shows the same so hopefully it was stable.

This is only my second A/G but previous kits fermented this way didn't finish as quickly which is why I was curious.

I take your point that the high temp could have caused a quicker fermentation and I will look at dropping the temp a bit in future as I would rather have a longer ferment. I agree the Tilt could be off due to the crud but I would assume the Tilt temp would be somewhere near.

Cheers
Dave
 
This is only my second A/G but previous kits fermented this way didn't finish as quickly which is why I was curious.
Did you use the same yeast as previous brews? Some yeast take their time, some rip through fermentation in 36 hours. No need to fret it - let the yeast do what they will do.
 
So it has been 7 days now - the Tilt shows 1012 and has been like that for 4 days. I have now checked with my Stevenson hydrometer which shows 1016! so no idea what's going on.

I remembered I bought a refractometer which I haven't used yet only to find I had bought a version with a Brix reading - idiot. Anyway this shows a reading of 6 so anyone know what this is in SG. I will trust the hydrometer reading.

I think my plan is to raise the temp for a couple of days then cold crash and call it done. Any thoughts out there?

Cheers
 
Floating hydrometers (tilt, pill, ispindel) can never be accurate at the end of fermentation as you get yeast clinging to the pill which will throw the reading off.

The tilt can never be accurate. Trust your hydrometer.

Tilt shows 1012 and has been like that for 4 days. I have now checked with my Stevenson hydrometer which shows 1016! so no idea what's going on

I remembered I bought a refractometer which I haven't used yet only to find I had bought a version with a Brix reading - idiot. Anyway this shows a reading of 6 so anyone know what this is in SG. I will trust the hydrometer reading.
It's a simple "multiply by a magic number to convert from brix to SG", so don't worry about having bought one with only brix reading. HOWEVER, because it's a mix of 3 different things (water, sugar, ethanol) you cannot calculate ABV/gravity with an end reading only. You need to take both an initial reading and a final reading with your refractometer to calculate the ABV/SG
 
So it has been 7 days now - the Tilt shows 1012 and has been like that for 4 days. I have now checked with my Stevenson hydrometer which shows 1016! so no idea what's going on.

I remembered I bought a refractometer which I haven't used yet only to find I had bought a version with a Brix reading - idiot. Anyway this shows a reading of 6 so anyone know what this is in SG. I will trust the hydrometer reading.

I think my plan is to raise the temp for a couple of days then cold crash and call it done. Any thoughts out there?

Cheers
Are you degassing the sample you are taking for the hydrometer?
 
It might be the yeast.

It's not one I'm familiar with so would be good to hear from others who have used this yeast. All yeasts have different characteristics and as you use them more, you get to know how they should perform. One thing I did find when searching for this yeast: "Pitching rate of 0.5 – 1g per litre is recommended. If fermenting wort at 20c and a SG of 1.050 2 sachets is recommended". I know your OG was lower that this, but sounds like you need more of this yeast than your typical yeasts like US05, so that could be the issue.

Some yeasts do slow down then get going again, so I would give it the full 2 weeks anyway. I'm 250 brews in and I never even look at my beer before day14.
 
I'm also a relative AG newbie and also had what I thought was a stalled fermentation this week. Had 20L of a blonde / pale ale brewed last weekend. M44 Mangrove Jacks yeast which seemed to take a while to get going but then went bananas for two days. FV is next to my desk where I work from home and the delightful and re-assuring sound of airlock activity bordered on annoying at times..

In any case, took a hydrometer reading last night and it had motored down to 1.008. Planning to transfer to keg sooner than planned (next weekend) as I don't want the FG to drop much further. Also wondering if my thermometer is out as I seem to be ending up with highly fermentable brews despite mashing at 67deg.. Preference would always be a lower ABV beer with more body to it...

Every day's a school day and all that :)

As an aside, what sort of FV are you cold crashing in? Given this has fermented so quickly, I'd like to cold crash this in the FV, but as it's only a plastic bucket type with airlock, I'm wary of air ingressing during the cold crash...
 
Transferring sooner will not stop fermentation at all it will still carry on fermenting down unless you drop the temp right down to make the yeast go to sleep but it will possibly wake back up once warmed again.
Let it ferment out fully it will also let the yeast clean up any impurities then cool down for a day or two then keg.
Ps if you are priming the keg it will use up any sugar left plus the priming sugar and may over carb it if you are doing that method
 
Thanks for the replies - if it is insufficient yeast can it be rescued? I am just tempted to cold crash and bottle it and move on.
Just checked the SG again with a hydrometer - 1018. Something not right here.
 
Didn't degass but I did spin the hydrometer athumb..
All spinning does is knock the bubbles off the hydrometer, de-gassing takes less than a minute, or let the sample stand for one hour.

Thanks for the replies - if it is insufficient yeast can it be rescued? I am just tempted to cold crash and bottle it and move on.
Just checked the SG again with a hydrometer - 1018. Something not right here.
I am 100% certain that the yeast has converted all the fermentable sugars and what you are left with is the unfermentable sugars. Common in stouts because of the speciality grain. If you doughed in too high or mashed too high that would also add to the non-fermentability of the wort.
If you want to be sure then do a force ferment on a sample and see if the gravity changes. I would put money on it not changing or the change would be miniscule.
 
Thanks Foxy,

Thinking the mash SG was high as the recipe was for 25l but I made 24l so that may be the reason.
 
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