Accidentally put extra half gallon of water in fermenter = lower gravity?

[brewing_wessels]

Extract recipe told me to top up the fermenter to 5 gallons. I accidentally 5.5 gallons. Didn't really seem like there was anything I could do to "undo" that, so I just pitched yeast and put the airlock on.

Fermentation looked good, after 2 weeks I saw no more activity.

16 days I took gravity reading 1.012
2 days later I took another one, still 1.012.

Recipe I used called for FG of 1.015 (based on OG 1.062 -- I did not take an initial reading though)

My question is, due to the extra water, should I expect a lower gravity reading and move to bottling? OR.. Is this considered a "stuck" fermentation? Or.. Do I just need to wait longer?

Recipe info-

American Brown Ale

8# Canadian Light LME
0.5# Briess Crystal Malt
0.5# Munton Fison Carapils Malt
0.25# Briess Chocolate

1oz Brewers gold hops 60min
1oz Columbus hops 15min
1oz Columbus hops 2 min

WYEAST 1056

At around 10 days, added 1oz Citra Hops to the fermenter (this part was not in the recipe, we just felt like trying it)

Thanks guys. Long time lurker, first time poster

 

[MrE_the_Great]

If your gravity held for multiple days at 1.012 then I would say the fermentation is finished. The lower finishing gravity you experienced just means that the yeast fermented the beer a little dryer. In fact I think your ABV would be up...

Assuming you hit the OG, you should be at around 6.5% ABV as it stands now. IF your OG was 1.062 and your FG was 1.015 then you would have 6.17% ABV.

You just finished dryer than the recipe estimated (and the recipe FG IS an estimate that revolves around a lot of variables like temp, time, pitch count...)

I would bottle/keg at this point and not be worried about it.

A stuck fermentation is when the yeast finish significantly higher than you expected. You finished lower than expected.

 

[ncbrewer]

Re you question about the extra water affecting FG - attenuation shouldn't be affected, so yes, FG should be lower - about 1.013 or 1.014 instead of 1.015. But as already pointed out, predicted FG is just an estimate. You should be fine. Congrats.

 

[raysmithtx]

Congrats on the brew. Here is probably more than you want to know....

To see how much the additional .5 gallons of water affected the OG, do this:

Original predicted OG 1.062, take the last two digits and multiply that times the original gallons of water. So 62*5=310. That was the projected amount of sugar in the wort.

But you diluted the wort with an additional .5 gallons so using the above formula:
310 (original sugar points) / 5.5 (actual amount of water) = 56. So the OG was actually 1.056.

Now to get the % ABV take the OG (1.056) -FG (1.012). Using only the numbers after the decimal, so .056-.012=.044.
.044*131 = ABV of 5.76%. The original recipe would have had 1.062-1.015, so 6.16% ABV.

The FG finishing lower than predicted actually increased the % ABV. If you had hit the predicted FG with the additional .5 gallons or water the % ABV would have been 5.37 vs. your beer of 5.76%.

On the other hand if you hadn't added the extra water you would have had a 6.55% ABV.

 

[brewing_wessels]

If your gravity held for multiple days at 1.012 then I would say the fermentation is finished. The lower finishing gravity you experienced just means that the yeast fermented the beer a little dryer. In fact I think your ABV would be up...

Assuming you hit the OG, you should be at around 6.5% ABV as it stands now. IF your OG was 1.062 and your FG was 1.015 then you would have 6.17% ABV.

You just finished dryer than the recipe estimated (and the recipe FG IS an estimate that revolves around a lot of variables like temp, time, pitch count...)

I would bottle/keg at this point and not be worried about it.

A stuck fermentation is when the yeast finish significantly higher than you expected. You finished lower than expected.

Re you question about the extra water affecting FG - attenuation shouldn't be affected, so yes, FG should be lower - about 1.013 or 1.014 instead of 1.015. But as already pointed out, predicted FG is just an estimate. You should be fine. Congrats.

Congrats on the brew. Here is probably more than you want to know....

To see how much the additional .5 gallons of water affected the OG, do this:

Original predicted OG 1.062, take the last two digits and multiply that times the original gallons of water. So 62*5=310. That was the projected amount of sugar in the wort.

But you diluted the wort with an additional .5 gallons so using the above formula:
310 (original sugar points) / 5.5 (actual amount of water) = 56. So the OG was actually 1.056.

Now to get the % ABV take the OG (1.056) -FG (1.012). Using only the numbers after the decimal, so .056-.012=.044.
.044*131 = ABV of 5.76%. The original recipe would have had 1.062-1.015, so 6.16% ABV.

The FG finishing lower than predicted actually increased the % ABV. If you had hit the predicted FG with the additional .5 gallons or water the % ABV would have been 5.37 vs. your beer of 5.76%.

On the other hand if you hadn't added the extra water you would have had a 6.55% ABV.

Thanks yall. I appreciate the math and details, I'm one of those people that likes to understand why. Initially I was confused between mr_e and raysmith, but I get it now.

I bottled today, smell was excellent. I'll know in a few weeks. This is my 2nd batch ever, first batch was great, hoping to go 2/2.

 

[MrE_the_Great]

Sorry for the confusion...I usually adjust by topping off during the boil rather than the fermenter...which is before I take my OG reading. The attenuation not being affected would be correct, which is why I love this site...I learn every time I'm on it.