Stuck fermentation

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Leard

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I'm 11 days into fermentation for my amber ale. 20L with a grain bill consisting of:

4kg Maris Otter
300g Simpsons Amber Malt
300g CaraAmber
350g Simpsons Medium Crystal

FG should be 1.011 but for the last 3-4 days it's been stuck at 1.017. I managed to achieved a higher effiency than I thought and so I ended up under pitching yeast by about 3 million cells (according to BeerSmith).

I've tried adding a couple teaspoons of yeast nutrient, I've given the bucket a shake, and I've turned the temperature up to 23 degrees. It may still start fermenting again, however as of last night I've had no luck and it's still stuck.

When I gave it a whiff it still had that sharp fermentation smell.

Shall I wait longer or is there anything else I can do?
 
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Ben034

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What was the yeast used and the OG? Hydrometer sample or refractometer? Mash temperature?
 

Leard

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What was the yeast used and the OG? Hydrometer sample or refractometer? Mash temperature?
Yeast was Mangrove Jacks M44. I've used a refractometer sample that has been adjusted according to the OG of 1.055. However I also used my hydrometer which I'm wary to trust since the tube I use to put it in is quite narrow so I'm not sure how much it's getting stuck on the sides. However it was more a less the same as the adjusted Brix reading of 1.017. Mash temperature was about 66 degrees for 75 minutes.
 

Ben034

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Ok - so attenuation is on the low side at 67%. You're right to expect a little more with this yeast. It's certainly possible that it was slightly underpitched, but could still be working slowly. Does the sample taste particularly sweet? Double check your hydrometer in water (reading 1.000).

If you have another packet of the same yeast, you could add half in but I would give it a few more days yet before doing anything. 2 weeks minimum.
 

Leard

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Ok - so attenuation is on the low side at 67%. You're right to expect a little more with this yeast. It's certainly possible that it was slightly underpitched, but could still be working slowly. Does the sample taste particularly sweet? Double check your hydrometer in water (reading 1.000).

If you have another packet of the same yeast, you could add half in but I would give it a few more days yet before doing anything. 2 weeks minimum.
I intend to do a proper hydrometer reading tonight once I've checked it's accuracy. Unfortunately I don't have any more of this yeast. I'll give it a good taste later as well. I think I'll wait 2 weeks and see what happens and then consider more yeast.
 

Rodcx500z

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I have used mj yeast in the past its very slow to get going and I remember it took about 3 weeks to get to fg, I would give it a bit longer, when you open the lid on fv do you get the gas tickle in your nostrils if so its still fermenting slowly
 

Leard

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I have used mj yeast in the past its very slow to get going and I remember it took about 3 weeks to get to fg, I would give it a bit longer, when you open the lid on fv do you get the gas tickle in your nostrils if so its still fermenting slowly
Yeah that's what I mean by the sharp fermentation smell. There's definitely something going on. I was just worried because it hasn't moved in about 3-4 days and I'm use to seeing a few gravity points less each day.

@Leard
Stuck fermentations here
Simple strategies for dealing with stuck fermentations
And if you don't trust your hydrometer reading because the tube might be too small, why not just lower it into the beer in the FV and take your reading direct (after you have first checked the its accuracy in clean water and then sanitising). That's what I do.
I will do this tonight. I've been relying on my refractometer so far, however it's probably useful to compare the two.
 

terrym

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I have used mj yeast in the past its very slow to get going and I remember it took about 3 weeks to get to fg, I would give it a bit longer, when you open the lid on fv do you get the gas tickle in your nostrils if so its still fermenting slowly
Surely if the FV is sealed as most are then CO2 will be present in the headspace whether its fermenting or not? If you have a standard plastic FV with an airlock the easiest way of determining whether a brew is still fermenting and CO2 being produced is to put four strips of cling film over rim of the FV and replace the lid, which then forms an effective seal to stop CO2 bypassing the airlock. That's what I do. And I dont bother sanitising the cling film since it comes straight off the roll.
 
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