# how many gravity points create unsafe bottle carb?

### Help Support Homebrew Talk:

#### Hankhill11

##### Well-Known Member
so as the title suggest, How many gravity points when bottle carbing is unsafe? if you have a cider that is at 1.008, but the yeast can take it down to .998, would that be considered unsafe pressures? is it .004 points? .010 points? just curious. How many gravity points does the standard 3/4ths cup of sugar increase 5 gallons?

most people will let a cider finish, then back sweeten and carb. and pasteurized if they used fermentables to sweeten.

just trying to work out a good safety zone. Thanks in advance.

note- i have had 2 bottles blow only during pasteurization, and it was my fault for letting one get a little over carbed, and i think the other was just an unseen issue with the bottle its self

#### Maylar

##### Supporting Member
HBT Supporter
I've seen conflicting reports on that. I've measured the change in gravity after adding the recommended sugar for 2.5 volumes of CO2 and it was less than .002 change. I've also measured the before and after gravity when sweetening/priming/pasteurizing and it was barely measurable, maybe 1 point. So... it doesn't take much.

One tsp of table sugar will raise 12 oz of water to 1.005 - how much sugar is in one of those fizz caps?

#### ncbrewer

##### Well-Known Member
At 46 ppg, 4.19 oz of cane sugar in 5 gallons (for about 2.5 volumes) raises gravity by .00015. So almost any remaining fermentables remaining at bottling time would be a potential for bottle bombs.

#### ncbrewer

##### Well-Known Member
Brain fart on my calculations - I'm recalculating and will post the update. (Can't seem to use the edit feature)

#### ncbrewer

##### Well-Known Member
Brain fart on my calculations - I'm recalculating and will post the update. (Can't seem to use the edit feature)
It's a difference of .0023 in gravity. Sorry for the misinformation.

#### worlddivides

##### Well-Known Member
If you are carbing with priming sugar, then just two points is dangerous. As NCBrewer mentioned (in his corrected post), just two points is how much 4 ounces of corn sugar per 5 gallons carbonates. So, if you carbonate it that much and it further ferments another two points, then you are essentially adding double the amount of carbonation you need.

I forget the exact calculations, but I remember reading how many CO2 volumes "one point" (0.001) was, but basically your bottles would explode long before 10 points, even assuming you bottled without adding any sugar.

OP

#### Hankhill11

##### Well-Known Member
Interesting information. The moral of the story is, best be sure your fermentation is complete. OR pasteurize. And it sounds like pasteurization(or chemical castration i guess) is almost a must. Unless you are doing a real potent brew and your at the max ABV for the yeast, i feel like some residual yeasts will be there working every last molecule of sugar. until pop. Thanks for the input all!