Help understanding attenuation. Infection maybe?

[Lit]

After making my first "big" batch there are some things that don't add up in my mind. Hope anyone can add some light.

Total batch size was 13.20 gallons (51L) at OG 1084.

Malts:
3,5oz (100gr) chocolate (978 EBC)
24lb 4oz (11kg) Munich (15 EBC)
24lb 4oz pounds (11kg) Viena (6 EBC)

I divided the wort into 2 buckets of 6.6 gallons (25L), one with US-05 (safeale) the other 6.6 gallons (25L)with nottingham (danstar).
A bit more than 1 month later FG reads 1032 (us-05) and 1030 (notti).

My guess: After some forum reading I end up blaming temperatures on the HLT denaturating enzymes, plus the low enzymatic power of the malts (first time using the HERMS setup, HLT water was at 75-80ºC recycling water without stop 60min).

I decided to bottle half of the buckets, and add Dry hopping and 250gr of sugar to attenuate a bit more, to each of wort left in the buckets.
A bit less than 1 and half month latter I bottled what is left in each bucket. The readings were 1024 (us-05) and 1011 (notti).

It is my guess about the high OG right? Is the second notti contaminated? Why is that FG that low if it isn't? Already opened some of the first bottled ones and both are OK with gas, so both of them were done fermenting at 1030/1032, they just taste a bit sweet. What's happening here? Pls no bully about the grain bill.

 

[morbster]

I don't think it is contaminated. With an OG of 1.084 and FG of 1.011, your attenuation was 86%, which is within the range for Nottingham. You didn't let fermentation finish before bottling.

Edit: from the manufacturer, Nottingham is capable of achieving an FG of 1.008.

 

[ncbrewer]

Since you got the FG a lot lower on the second half, I'm guessing it's a yeast health issue. Whether that's right or not, I'd be very careful with the early bottles. Sometimes, yeast will get going again. You could get bottle bombs.

 

[Lit]

I don't think it is contaminated. With an OG of 1.084 and FG of 1.011, your attenuation was 86%, which is within the range for Nottingham. You didn't let fermentation finish before bottling.

Edit: from the manufacturer, Nottingham is capable of achieving an FG of 1.008.

But then, why I'm not having bottle bombs, just regular gassed beers, from the first bottled notti batches at 1030? By that logic those should have lowered a lot too.

 

[Lit]

Since you got the FG a lot lower on the second half, I'm guessing it's a yeast health issue. Whether that's right or not, I'd be very careful with the early bottles. Sometimes, yeast will get going again. You could get bottle bombs.

The eartly bottles are now 1 and half months old since bottled. They aren't even a lot carbonated, just standard.

 

[morbster]

I'm trying to make sure I follow. Your beer that was bottled at 1.030 and is now at 1.011 isn't carbonated?

Are these conventional glass bottles with metal caps?

 

[Lit]

I'm trying to make sure I follow. Your beer that was bottled at 1.030 and is now at 1.011 isn't carbonated?

Are these conventional glass bottles with metal caps?

Sorry, I know my english isn't the best. I will try to summarize it better.

- Make total wort
- Divide the wort into 2 fermenters, lets call them notti and us-05.
- 1 month later
- Readings show 1030 the notti one, and 1032 the us-05
- Bottle HALF of each fermenter volume. Lets call them beer-notti-1 and beer-us05-1.
- Add 8.8oz (250gr) of suggar to each fermenter (the halfs not bottled).
- 1,5 months later.
- Readings show 1011 the notti one, and 1024 the us-05.
- Bottle the remaining halfs. Lets call them beer-notti-2 and beer-us05-2.
- 1 week later start worring about it and post it here (present).

As of now, beer-notti-1 and beer-us05-1 have normal quantity of gas, that is what makes me think that they did finish fermenting. This also would explain the high-but-lower FG of the beer-us05-2 after fermenting the added suggar. Question is about what happened to beer-notti-2 to get a FG that low, when it didn't on beer-notti-1.
I hope this makes it a bit clearer.

Additional note: All the readings were done with the same hydrometer, tested first with water.

 

[morbster]

What did you add 8.8oz of to each fermenter?

Your fermentation may have stalled, which would explain why you didn't have bottle bombs.

Try taking a gravity reading of one of your bottled beers. Let the sample from that bottle degas for a bit since the CO2 will affect your reading.

 

[Lit]

What did you add 8.8oz of to each fermenter?

Your fermentation may have stalled, which would explain why you didn't have bottle bombs.

Try taking a gravity reading of one of your bottled beers. Let the sample from that bottle degas for a bit since the CO2 will affect your reading.

Edited to add the info. I added 8.8oz of sugar to each of fermenters (3.3 gallons left each).

If it stalled, that means only un-stalled the beer-notti-2 and not the others (beer-notti-1, beer-us05-1 and beer-us05-2)?

 

[ncbrewer]

I'm still thinking a yeast health issue. It sounds like the sugar you added was easy to ferment, so fermentation re-started in the fermenters. The yeast might be pretty much pooped out, so it's unpredictable.

 

[morbster]

I agree with ncbrewer. I think that your yeasts stalled out during fermentation, either from underpitching, inadequate wort aeration, fermentation temperature issues, or simply bottling too early.

Adding the half pound of sugar probably helped revitalize the yeast that were going dormant.

I would not expect an infection or bottle bombs with your current bottles.