Why is my FG so high? 1.040

[MagicMike314]

I left my beer for a whole month in the primary, it seemed to have a very healthy fermentation and was kept at a constant temperature of 66 degrees. As I bottled today, I made the mistake of checking the FG after everything was bottled. Came out WAY TOO HIGH at 1.040. Recipe included 3/4 pounds of lactose but otherwise was the same as any of the other couple batches I had made. OG was right on the money (and yes I was using a hydrometer). I pitched a pack and a half of US-05.

Original Gravity: 1.079
Final Gravity: 1.010
ABV: 7.9%

This was what was calculated by BeerSmith for what I should expect. Tasted some of the beer and it was very sweet.

Very confused as to what has gone wrong.

 

[VikeMan]

What were your grain bill specifics, your mash temp (actual, not planned), and mash length?

 

[Silver_Is_Money]

I was about to suggest the problem was a refractometer, and then I read it again....

 

[grampamark]

Ask the obvious first-did you have enough in your sample cylinder to ensure that the hydrometer floated instead of bottoming out?

 

[MagicMike314]

I used a hydrometer for both OG and FG. I still use extract so here was what was used.

8 lb Light DME
1 lb Honey Malt
.2 lb Black Patent

 

[MagicMike314]

Ask the obvious first-did you have enough in your sample cylinder to ensure that the hydrometer floated instead of bottoming out?

That was my first thought as well - so I made sure to add plenty in there!

 

[MagicMike314]

The only other thing I could think of was using an aquarium pump of sorts for oxygen for the first time. It seemed to be working great in a glass of water but maybe there wasn't enough oxygen introduced to the wort.

 

[VikeMan]

8 lb Light DME
1 lb Honey Malt
.2 lb Black Patent

Plus 0.75 pounds lactose, right?

Hmmm. Even assuming that none of the gravity from the honey malts was fermentable (an oversimplification, but it really should be mashed with a base malt, not steeped), I'd predict an FG of about 1.024. But there was no way this was ever going to get close to 1.010.

My only obvious guess as to why it would have stopped at 1.040 would be low yeast vitality/viability. That's a bit less likely given you used dry yeast though.

The only other thing I could think of was using an aquarium pump of sorts for oxygen for the first time. It seemed to be working great in a glass of water but maybe there wasn't enough oxygen introduced to the wort.

You could skip aeration altogether and I wouldn't expect an FG as high as you got.

What kind of DME was this? Not any sort of "off brand" by any chance?

And are you sure about your 66F temperature? If it were much lower, it could have been a sluggish fermentation that wasn't finished yet.

 

[MagicMike314]

Plus 0.75 pounds lactose, right?

Hmmm. Even assuming that none of the gravity from the honey malts was fermentable (an oversimplification, but it really should be mashed with a base malt, not steeped), I'd predict an FG of about 1.024. But there was no way this was ever going to get close to 1.010.

My only obvious guess as to why it would have stopped at 1.040 would be low yeast vitality/viability. That's a bit less likely given you used dry yeast though.



You could skip aeration altogether and I wouldn't expect an FG as high as you got.

What kind of DME was this? Not any sort of "off brand" by any chance?

And are you sure about your 66F temperature? If it were much lower, it could have been a sluggish fermentation that wasn't finished yet.

Yes the lactose as well! I used the regular Breiss stuff that I've used in the past. I'm pretty confident in the temperature! It certainly could drop lower in these Michigan winters in the basement - but I have one of those disposable thermometers taped to the side of the carboy and it was always at 66.

With everything bottled - is it destined for bottle bombs?

 

[VikeMan]

With everything bottled - is it destined for bottle bombs?

If I were you, I'd keep these bottles very cold and protected after carbonation. And before that, I'd be checking for "full" carbonation frequently.

 

[MagicMike314]

I saved about 200 ml of the last of it - and added some regular baking yeast with a heating pad. I'll see in a day or two if the gravity has dropped. But if it has - there's not much that can be done correct? I would assume oxygen is too much of an enemy at this point to do anything else

 

[Transamguy77]

Couple of things, did you measure after adding your priming sugar? Since it’s an extract batch is could have not just finished sometimes extract will just stall a bit short of the predicted FG. And your lactose will bring that up more and as @VikeMan said there is no way it would ever get to 1.010. I do a big stout that is 1.075 and finishes in the high 1020’s so I don’t think your that far off.

 

[VikeMan]

I saved about 200 ml of the last of it - and added some regular baking yeast with a heating pad. I'll see in a day or two if the gravity has dropped. But if it has - there's not much that can be done correct? I would assume oxygen is too much of an enemy at this point to do anything else

Personally, I wouldn't try to transfer bottled beer back to a fermenter. That's pretty much a recipe for an oxidized mess.

 

[MagicMike314]

Couple of things, did you measure after adding your priming sugar? Since it’s an extract batch is could have not just finished sometimes extract will just stall a bit short of the predicted FG. And your lactose will bring that up more and as @VikeMan said there is no way it would ever get to 1.010. I do a big stout that is 1.075 and finishes in the high 1020’s so I don’t think your that far off.

I did measure after the priming sugar! Thanks for that thought - it hadn't even crossed my mind. I just measured the FG one more time (after letting it sit and settle out) and it's closer to 1.034. With the lactose and priming sugar is this more where you would expect the FG to finish out?

 

[VikeMan]

I did measure after the priming sugar! Thanks for that thought - it hadn't even crossed my mind. I just measured the FG one more time (after letting it sit and settle out) and it's closer to 1.034. With the lactose and priming sugar is this more where you would expect the FG to finish out?

I'd expect 1.024 (or a little lower). Add priming sugar and you're looking at maybe 1.027 (depending on how much you added.

 

[Transamguy77]

I did measure after the priming sugar! Thanks for that thought - it hadn't even crossed my mind. I just measured the FG one more time (after letting it sit and settle out) and it's closer to 1.034. With the lactose and priming sugar is this more where you would expect the FG to finish out?

Yes that sounds a bit more realistic, after priming I’d think it’ll drop 6-8 more points which is where I’d expect to see it finish.
I have found that S05 and 1056 always finish right at or right around 1.010 so I could see why that was predicted without the lactose.

 

[VikeMan]

Yes that sounds a bit more realistic, after priming I’d think it’ll drop 6-8 more points which is where I’d expect to see it finish.

You'd need almost 13 ounces of sucrose in 5 gallons to add 7 points.

 

[VikeMan]

I have found that S05 and 1056 always finish right at or right around 1.010 so I could see why that was predicted without the lactose.

Without knowing the fermentability of the wort and the OG, no yeast strain always (or even usually) finishes at a given FG. It's much more complicated than just looking at some manufacturer's published average attenuation number for a strain, but even if it wasn't, the starting OG matters too. i.e. 75% apparent attenuation (for example) for a 1.100 beer lands at 1.025, but the same attenuation for a 1.050 beer lands at 1.012/1.013.

When predicting attenuation, Beersmith considers some of the important factors, but not all. But if you scale a batch to a higher (or lower) OG, Beersmith certainly doesn't predict the same FG for both batches.

 

[Transamguy77]

@VikeMan That is my personal experience, no matter what the gravity up to like 1.080 10 gallons will ferment that low every time, maybe you have different experiences but that’s mine.

 

[VikeMan]

@VikeMan That is my personal experience, no matter what the gravity up to like 1.080 10 gallons will ferment that low every time, maybe you have different experiences but that’s mine.

I can't comment on your personal experience, but I can promise you that BeerSmith didn't predict the FG of 1.010 based on your (or anyone's) experience of US-05 "typically" finishing around 1.010. Its models don't work that way.

I can however comment on my own personal experience. Depending on OG and fermentability of the wort, I have had Chico strain batches finish anywhere from ~1.008 to ~1.050. Very predictably, too, generally within a point or two.