[HopDen]

I brewed a BGSA in the early part of 23, kegged in March. The beer did not attenuate completely and is cloying. OG est.1.080/ act.1.071 and FG was est. at 1.010/ act. 1.023

Beer has been kept cold and uncarbed except a quick 30psi blast to set the lid at kegging.

I was thinking that to "fix" the issue I could add fresh yeast (WLP570) and some dextrin and bottle into some swing top bottles.
I have a few questions, 1) Is added sugar necessary?
                                  2) Should I use the same yeast strain or can I use a neutral lager yeast?
                                  3) I assume swing tops are safe, are they safe for bottle conditioning at say 3.5-4 volumes?
I will be bottling 5 gallons.

I have never bottled beer or bottle conditioned so any help is greatly appreciated.

[denny]

I brewed a BGSA in the early part of 23, kegged in March. The beer did not attenuate completely and is cloying. OG est.1.080/ act.1.071 and FG was est. at 1.010/ act. 1.023

Beer has been kept cold and uncarbed except a quick 30psi blast to set the lid at kegging.

I was thinking that to "fix" the issue I could add fresh yeast (WLP570) and some dextrin and bottle into some swing top bottles.
I have a few questions, 1) Is added sugar necessary?
                                  2) Should I use the same yeast strain or can I use a neutral lager yeast?
                                  3) I assume swing tops are safe, are they safe for bottle conditioning at say 3.5-4 volumes?
I will be bottling 5 gallons.

I have never bottled beer or bottle conditioned so any help is greatly appreciated.

If I understand correctly,  you're hoping for further attenuation in the bottles? If so, bad idea. If you just want to bottles, though, you need to figure out why it was underattenuated so you don't end up with bottle bombs. If you do need to add yeast, any strain will do.

[neuse]

I brewed a BGSA in the early part of 23, kegged in March. The beer did not attenuate completely and is cloying. OG est.1.080/ act.1.071 and FG was est. at 1.010/ act. 1.023

Beer has been kept cold and uncarbed except a quick 30psi blast to set the lid at kegging.

I was thinking that to "fix" the issue I could add fresh yeast (WLP570) and some dextrin and bottle into some swing top bottles.
I have a few questions, 1) Is added sugar necessary?
                                  2) Should I use the same yeast strain or can I use a neutral lager yeast?
                                  3) I assume swing tops are safe, are they safe for bottle conditioning at say 3.5-4 volumes?
I will be bottling 5 gallons.

I have never bottled beer or bottle conditioned so any help is greatly appreciated.

If I understand correctly,  you're hoping for further attenuation in the bottles? If so, bad idea. If you just want to bottles, though, you need to figure out why it was underattenuated so you don't end up with bottle bombs. If you do need to add yeast, any strain will do.

If I was adding yeast, I would use a strain that was rated for the same or lower attenuation than the yeast originally used - to avoid getting unwanted additional attenuation.
(I would also be very uncomfortable with going for further attenuation in the bottles.)

[denny]

I brewed a BGSA in the early part of 23, kegged in March. The beer did not attenuate completely and is cloying. OG est.1.080/ act.1.071 and FG was est. at 1.010/ act. 1.023

Beer has been kept cold and uncarbed except a quick 30psi blast to set the lid at kegging.

I was thinking that to "fix" the issue I could add fresh yeast (WLP570) and some dextrin and bottle into some swing top bottles.
I have a few questions, 1) Is added sugar necessary?
                                  2) Should I use the same yeast strain or can I use a neutral lager yeast?
                                  3) I assume swing tops are safe, are they safe for bottle conditioning at say 3.5-4 volumes?
I will be bottling 5 gallons.

I have never bottled beer or bottle conditioned so any help is greatly appreciated.

If I understand correctly,  you're hoping for further attenuation in the bottles? If so, bad idea. If you just want to bottles, though, you need to figure out why it was underattenuated so you don't end up with bottle bombs. If you do need to add yeast, any strain will do.

If I was adding yeast, I would use a strain that was rated for the same or lower attenuation than the yeast originally used - to avoid getting unwanted additional attenuation.
(I would also be very uncomfortable with going for further attenuation in the bottles.)

How do you know yeast was the original problem? Did you do a forced ferment test? Yeast is the least reliable way to control attenuation.

[neuse]

I brewed a BGSA in the early part of 23, kegged in March. The beer did not attenuate completely and is cloying. OG est.1.080/ act.1.071 and FG was est. at 1.010/ act. 1.023

Beer has been kept cold and uncarbed except a quick 30psi blast to set the lid at kegging.

I was thinking that to "fix" the issue I could add fresh yeast (WLP570) and some dextrin and bottle into some swing top bottles.
I have a few questions, 1) Is added sugar necessary?
                                  2) Should I use the same yeast strain or can I use a neutral lager yeast?
                                  3) I assume swing tops are safe, are they safe for bottle conditioning at say 3.5-4 volumes?
I will be bottling 5 gallons.

I have never bottled beer or bottle conditioned so any help is greatly appreciated.

If I understand correctly,  you're hoping for further attenuation in the bottles? If so, bad idea. If you just want to bottles, though, you need to figure out why it was underattenuated so you don't end up with bottle bombs. If you do need to add yeast, any strain will do.

If I was adding yeast, I would use a strain that was rated for the same or lower attenuation than the yeast originally used - to avoid getting unwanted additional attenuation.
(I would also be very uncomfortable with going for further attenuation in the bottles.)

How do you know yeast was the original problem? Did you do a forced ferment test? Yeast is the least reliable way to control attenuation.

I might not have made my concern clear. I wasn't thinking of solving the problem with yeast choice. My reasoning is that using a higher attenuating yeast for bottling, even in normal circumstances without an attenuation concern, would tend to ferment more of the sugars - not just the priming sugar. I want just the priming sugar to ferment in the bottle so that I can predict the CO2 volumes.

[BrewBama]

A cpl questions: How did you measure your gravity?  Did you originally use a diastaticus strain?

I believe whatever yeast strain you used, it has consumed all the sugars the strain is capable of.

If you did not use a diastaticus strain you may try that in the fermenter*.  Diastaticus strains can metabolize complex sugars into simple sugars so it can consume them.

Another approach could be to use enzymes that break down complex sugars so yeast can consume them.

There are pros and cons to each approach.

If you did use a diastaticus strain, I can’t imagine there are any more sugars to consume. Which leads me to my first Q.

* I would not try to increase attenuation in a bottle

[chinaski]

I think that your plan will create more headaches than it will solve.  When I have had similar underattenuated beers, I prefer to blend the batch with some really dry beer- this is often a similar recipe that has been tweaked to ferment out to a much lower FG to balance the original brew.  Depending on the beer's grain-bill this might mean removing crystal malts, adding sugar, mashing lower temp and dropping the OG of the blend-in recipe.  Once I'm ready to blend, I transfer half of the original brew into a clean keg and then transfer halves of the blend-in to the two kegs of beer.  This can work very well and serves as a really good test of my brewing knowledge to get a blend-in that does what I need it to.

[HopDen]

I brewed a BGSA in the early part of 23, kegged in March. The beer did not attenuate completely and is cloying. OG est.1.080/ act.1.071 and FG was est. at 1.010/ act. 1.023

Beer has been kept cold and uncarbed except a quick 30psi blast to set the lid at kegging.

I was thinking that to "fix" the issue I could add fresh yeast (WLP570) and some dextrin and bottle into some swing top bottles.
I have a few questions, 1) Is added sugar necessary?
                                  2) Should I use the same yeast strain or can I use a neutral lager yeast?
                                  3) I assume swing tops are safe, are they safe for bottle conditioning at say 3.5-4 volumes?
I will be bottling 5 gallons.

I have never bottled beer or bottle conditioned so any help is greatly appreciated.

If I understand correctly,  you're hoping for further attenuation in the bottles? If so, bad idea. If you just want to bottles, though, you need to figure out why it was underattenuated so you don't end up with bottle bombs. If you do need to add yeast, any strain will do.

Yes, hoping to ferment it to a drier FG. I haven't a clue as to why it did not complete. I had a healthy starter pitch. Pitched around 67 and let it free rise to 78 and then held there. I believe it petered out about the time it reached 78* I really don't know why?

[HopDen]

A cpl questions: How did you measure your gravity?  Did you originally use a diastaticus strain?

I believe whatever yeast strain you used, it has consumed all the sugars the strain is capable of.

If you did not use a diastaticus strain you may try that in the fermenter*.  Diastaticus strains can metabolize complex sugars into simple sugars so it can consume them.

Another approach could be to use enzymes that break down complex sugars so yeast can consume them.

There are pros and cons to each approach.

If you did use a diastaticus strain, I can’t imagine there are any more sugars to consume. Which leads me to my first Q.

* I would not try to increase attenuation in a bottle

So after verifying WLP570 is a diastaticus strain. I will have to educate myself on the variable. Maybe it would be a better approach to try and further ferment it in a carboy or corny keg.

[HopDen]

I think that your plan will create more headaches than it will solve.  When I have had similar underattenuated beers, I prefer to blend the batch with some really dry beer- this is often a similar recipe that has been tweaked to ferment out to a much lower FG to balance the original brew.  Depending on the beer's grain-bill this might mean removing crystal malts, adding sugar, mashing lower temp and dropping the OG of the blend-in recipe.  Once I'm ready to blend, I transfer half of the original brew into a clean keg and then transfer halves of the blend-in to the two kegs of beer.  This can work very well and serves as a really good test of my brewing knowledge to get a blend-in that does what I need it to.

I blended the first 2 kegs with a German Pilz. Very technical on my part....pour half glass of the pilz and half glass of the BGSA. Prob not the best way to do but it worked. As stated above, I have never bottled beer or bottle conditioned so I thought about fermenting it to completion in the bottle but from what I'm reading, not a bright idea.

[jjflash]

Here is my fix:
For carbonated keg - out gas all CO2.
Pull the lid pressure valve several times.
Finally de-gas by putting gas side to blow off tube in water, I use 3L soda bottle.
When fully outgassed add Convertase AG300 or similar as likely you do not have full conversion.
Add neutral dry yeast. 
I like Lalvin EC-1118 as it is both alcohol and pH tolerant.
Put blow off tube back on.
Temperature 72-77 degrees.
Ferment till done.

Downside: 
You have no control over fermentation once Convertase is added.
(Could add NaMBS like the wine guys to stop further fermentation but I do not recommend)
You may drop 10 points or more.
I have had a couple kegs go below 1.000 with this method.
Quite surprizing to me the beer was not hot and still very drinkable!
I would drink this beer any day over underattenuated Belgian beers.

[HopDen]

Here is my fix:
For carbonated keg - out gas all CO2.
Pull the lid pressure valve several times.
Finally de-gas by putting gas side to blow off tube in water, I use 3L soda bottle.
When fully outgassed add Convertase AG300 or similar as likely you do not have full conversion.
Add neutral dry yeast. 
I like Lalvin EC-1118 as it is both alcohol and pH tolerant.
Put blow off tube back on.
Temperature 72-77 degrees.
Ferment till done.

Downside: 
You have no control over fermentation once Convertase is added.
(Could add NaMBS like the wine guys to stop further fermentation but I do not recommend)
You may drop 10 points or more.
I have had a couple kegs go below 1.000 with this method.
Quite surprizing to me the beer was not hot and still very drinkable!
I would drink this beer any day over underattenuated Belgian beers.

Interesting! I like the idea of using wine yeast to finish it out/dry. I have used that yeast many times with wine.

[denny]

Here is my fix:
For carbonated keg - out gas all CO2.
Pull the lid pressure valve several times.
Finally de-gas by putting gas side to blow off tube in water, I use 3L soda bottle.
When fully outgassed add Convertase AG300 or similar as likely you do not have full conversion.
Add neutral dry yeast. 
I like Lalvin EC-1118 as it is both alcohol and pH tolerant.
Put blow off tube back on.
Temperature 72-77 degrees.
Ferment till done.

Downside: 
You have no control over fermentation once Convertase is added.
(Could add NaMBS like the wine guys to stop further fermentation but I do not recommend)
You may drop 10 points or more.
I have had a couple kegs go below 1.000 with this method.
Quite surprizing to me the beer was not hot and still very drinkable!
I would drink this beer any day over underattenuated Belgian beers.

Interesting! I like the idea of using wine yeast to finish it out/dry. I have used that yeast many times with wine.

I have had bad to no luck with wine yeast.

[BrewBama]

The key is the Convertase AG300. Careful though.

[denny]

Frankly, I would either drink it as is or dump it, then brew another one. Trying a major "fix" like that has seldom worked out well for me. It may be easier and more successful to rebrew.