question about final gravity

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oldwinemaker

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I'm brewing from a kit and the instructions say the final gravity should be 1.016. My question is. Is it safe to assume the lower the final gravity, the lesser of a chance of getting bottle bombs?
 

JordanThomas

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Ummmm, no. Bottle bombs are caused by fermentables being converted in the bottle and over-pressurizing. If your FG is stable, that means your yeast no longer want to eat the remaining sugars in your bottles. If you add more yeast at bottling, then you might want to worry about that. Also, make sure you only prime with the appropriate amount of priming sugar. Over priming can cause boomers, too.
 

Matt3989

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Final gravity is when all of your fermentable sugars have been processed by your yeasties. So there should only be one final gravity, and it is very easily calculable for extract brews. But once your gravity has stabilized for a few days, you're usually there (unless the you dropped the temp down to 33dF or something and put your yeast to sleep).

Bottle bombs are usually caused by too much sugar when you prime (add more sugar to the beer before bottling so the yeast carbonate your bottles), but sometimes people bottle too soon so they get the co2 from the priming sugar, as well as from the left over fermentables = too much pressure and exploding bottles.

I would say, once you think you've hit your FG, give the beer another week in the fermenter (the yeast will reabsorb and lessen the off flavors) and you'll be completely sure you've hit your desired FG.
 

J187

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Final gravity is when all of your fermentable sugars have been processed by your yeasties. So there should only be one final gravity, and it is very easily calculable for extract brews. But once your gravity has stabilized for a few days, you're usually there (unless the you dropped the temp down to 33dF or something and put your yeast to sleep).

Bottle bombs are usually caused by too much sugar when you prime (add more sugar to the beer before bottling so the yeast carbonate your bottles), but sometimes people bottle too soon so they get the co2 from the priming sugar, as well as from the left over fermentables = too much pressure and exploding bottles.

I would say, once you think you've hit your FG, give the beer another week in the fermenter (the yeast will reabsorb and lessen the off flavors) and you'll be completely sure you've hit your desired FG.

Hmm... not sure I agree with a week in the fermenter after you've reached a steady gravity...

I'd say for most ales, a better approach is to time it so it will be roughly about 2 weeks in primary - taking a gravity reading once at 11-12 days and once at 14, the gravity should be stable and around what you expect - at that point, you're good to bottle. This will have already included time for the yeast to clean up, whereas primary stage of fermentation should have completed within the first few days.
 

Han_Solo

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What is "too much" sugar? I ask because I recently added sugar for 5 gallons to a 4-4.5 gallon batch. Is that enough to cause bombs?
 

J187

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What is "too much" sugar? I ask because I recently added sugar for 5 gallons to a 4-4.5 gallon batch. Is that enough to cause bombs?
What level of carbonation were you trying to get into your beer with the calculations? "sugar for 5 gallons" doesn't really tell us much, 5 gallons worth of sugar for 1.5 vols of carb is much different than 4 galls worth for 3.5 vols.
 

JordanThomas

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What is "too much" sugar? I ask because I recently added sugar for 5 gallons to a 4-4.5 gallon batch. Is that enough to cause bombs?
As the poster above mentioned... if you were carbing close to the max already, you might have a problem. If you were carbing to 2.0 volumes, the extra gallon (assuming you only had 4 gallons) might only put you at 0.5 volumes, or 2.5 total. That would still be okay. Now, if you were carbing to 2.5 volumes calculated for 5 gallons and only had 4 gallons, you would have approximately carbonated to 3.125 volumes. THAT, might be cause for boom-booms.
 

Han_Solo

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J187 said:
What level of carbonation were you trying to get into your beer with the calculations? "sugar for 5 gallons" doesn't really tell us much, 5 gallons worth of sugar for 1.5 vols of carb is much different than 4 galls worth for 3.5 vols.
I wasn't really targeting a certain level. I am pretty new to brewing and 4.5 oz of dextrose is what the LHBS gives you when you purchase a kit. When my batch came up a little under I didn't even think to adjust how much sugar to use. I am not sure what the volumes refer to or how they work but basically I used 4.5 oz for about 4.25 gallons and am kind of worried a bunch of the bottles will burst
 

JordanThomas

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I wasn't really targeting a certain level. I am pretty new to brewing and 4.5 oz of dextrose is what the LHBS gives you when you purchase a kit. When my batch came up a little under I didn't even think to adjust how much sugar to use. I am not sure what the volumes refer to or how they work but basically I used 4.5 oz for about 4.25 gallons and am kind of worried a bunch of the bottles will burst
That's 2.8 volumes, assuming you have exactly 4.25 gallons. That is on the higher range for most normal bottles, but should be perfectly safe. Did you make sure you stirred your beer after you added your sugar, or did you heat it with a mixture of water before adding? Both are good ideas to ensure that the priming sugar is properly distributed.
 

J187

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I wasn't really targeting a certain level. I am pretty new to brewing and 4.5 oz of dextrose is what the LHBS gives you when you purchase a kit. When my batch came up a little under I didn't even think to adjust how much sugar to use. I am not sure what the volumes refer to or how they work but basically I used 4.5 oz for about 4.25 gallons and am kind of worried a bunch of the bottles will burst
Oh yea, You may not love the carbonation level of your beer... but you aren't going to be blowing any bottles up. I think the max is about 4 vols before the regular brown bottles start to explode. My advice is to become familiar with what carbonation levels feel like when you drink your beer and see what you like, then alter for the style if you wish. I like about 2.3 in most ales, but I will go up or down a bit depending on the style. I carb with table sugar and I use online calculators to figure out how much. I ALWAYS measure my sugar in weight, given the crazy variation of dry volume of a crystal-like substance such as sugar. In other words, pour sugar into a measuring cup until you have 1 cup, 5 different times, and you will have a different amount (in weight) all 5 times - depending on how the crystals fall and compact.

What kind of beer are we talking about?
 

Han_Solo

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To answer both questions, I mixed the sugar into water and it was an oatmeal stout. I've had a few since I bottled it about 6 weeks ago. It's definitely carbonated more than I would like, but it wasn't ruined either. Until that batch it didn't even occur to me to try carbing to style so I used a calculator for my last batch. It's a little more work but it makes it more entertaining.
 

JordanThomas

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To answer both questions, I mixed the sugar into water and it was an oatmeal stout. I've had a few since I bottled it about 6 weeks ago. It's definitely carbonated more than I would like, but it wasn't ruined either. Until that batch it didn't even occur to me to try carbing to style so I used a calculator for my last batch. It's a little more work but it makes it more entertaining.
Unfortunately that's probably the WORST style to have carb'd high! Hey, at least they won't blow up!
 
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