Gravity Unit question

Hey guys,

So I'm brewing a half-batch recipe. I took a gravity measurement with my hydrometer after chilling the wort and it came out to 1.068, but when I poured it into my fermenter, I found that I needed to add 0.5 gal of water to bring it to 3 gallons.

I forgot to take a second reading after adding the extra water. I'm looking through the brewing books that I have to calculate the new GU, but having a hard time figuring it out.

Could anyone out there please lend a hand?

Thank you!

The math is Vol1 x SG1 = Vol2 x SG2. In this case, 2.5 x 68 = 3 x SG2. The gravity after you add half a gallon will be about 1.057.

Man, you made that easy... too easy. I feel a few IQ points have been knocked out of me.

Thanks for your help. It makes sense. I guess I can use the equation next time to hit a specific gravity as well.

DinoCow said:

Man, you made that easy... too easy. I feel a few IQ points have been knocked out of me.

Thanks for your help. It makes sense. I guess I can use the equation next time to hit a specific gravity as well.

Click to expand...

Absolutely. It's a beautiful equation.

And it comes *really* useful with all-grain where after you mash you have a *pre*-boil (no evaporation and boil-off yet) and want to calculate what your O.G. is going to be after you boil off a gallon or so.

So...Very similar, lots of new equipment (plate chiller, pump, burners) and did something similar. Took the SG prior to boil then got caught up in all the gadgets and doing everything just right, forgot to take a OG reading going in to the fermenter until I was reviewing and updating Beersmith. I had 1.05 SG with 7.5 gallons, then ended up with 5 gallons in to fermenter. I estimate around 1/2 gallon in BK and plate chiller. Looks like a OG of around 68. Glad I found a couple of these threads so I can continue adjusting my equipment!