Little help for a new fella?

[RyanVTBrew]

I've brewed a few all grain batches, and have hit pre boil grav every time. I was shooting for a 1.079 this time, and came up with 1.052 in the pre boil. I have some dme, can I use that to jack up the gravity? If so, how much? Thanks in advance


Green mountain high!

 

[RyanVTBrew]

I just finished sparging, just turned the burner on.


Green mountain high!

 

[RyanVTBrew]

Anyone?


Green mountain high!

 

[burninator]

What post boil gravity are you looking for? That seems more critical, since boiling will raise OG.

 

[RyanVTBrew]

Original gravity should be 1.079 in a 5 gallon batch. I collected 7 gallons of wort at a 1.052. Now that you mention boiling, I feel dumb. If I boiled down to 5.5-6 gallons should I be close?


Green mountain high!

 

[burninator]

Original gravity should be 1.079 in a 5 gallon batch. I collected 7 gallons of wort at a 1.052. Now that you mention boiling, I feel dumb. If I boiled down to 5.5-6 gallons should I be close?


Green mountain high!

I'm just doing the math in my head, so don't take my word for it, but I think you'll come up a little short. Think closer to 1.070, but that's just my rough claculation.

 

[smcinco]

Here you go:

http://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/

 

[RyanVTBrew]

Thanks guys, my nerves are at ease


Green mountain high!

 

[passedpawn]

As you boil, the specific gravity goes up (sugars don't vaporize, only the water). Some math to figure out how much to boil off.

[I]       C1*V1 
V2 =  ------  (C  = concentration, or gravity points     V = volume)
        C2
[/I]

C1 was 52. V1 was 7g. C2 wants to be 79.

[I](52 * 7)
-------- = 4.6g
   79
[/I]

You needed to boil down to 4.6g to get your intended gravity.

It's OK to add DME at any time during the boil.

 

[RyanVTBrew]

A lb of dme should set my grav perfect. Should I add this at the end of the boil?


Green mountain high!

 

[RyanVTBrew]

And my question was already answered. Awesome. Thanks


Green mountain high!

 

[william_shakes_beer]

Another way to think about the beer math if you're a visual person like me: once you pull the bag you aren't changing the volume of sugar during the boil, only the amount of water its dissolved in. Present gravity X present water = total sugar. Divide by post boil water = post boil gravity.