Changing pre-boil gravity

Methods, ingredients, advice and equipment specific to all-grain (mash), partial mash (mini mash) and "brew in a bag" (BIAB) brewing.
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Cadbury
Posts: 74
Joined: Thursday Dec 27, 2007 8:24 pm

Changing pre-boil gravity

Post by Cadbury »

G'day men,
I have been told that I can adjust my pre-boil gravity by adding either malt or water. If my target pre-boil gravity is 1.039 and the actual pre-boil gravity is lets say 1.050, what do I do? If I have to add one or the other, how much would be needed to bring it down to 1.039 in a 30L batch?
Many thanks
Cadbury
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warra48
Posts: 2082
Joined: Wednesday Apr 04, 2007 12:45 pm
Location: Corlette NSW

Re: Changing pre-boil gravity

Post by warra48 »

What's wrong with 1.050 ???

Anyway, it's a simple equation.

For example, say you have 30 litres @ 1.050.
You want to get it down to 1.039.
Thus 30 x 50 = 1500 ÷ 39 = 38.5 litres.
Therefore, add 8.5 litres of water.

Remember, if you increase the volume of your beer, you'll need to adjust your hopping schedule to allow for the changed volume and gravity.
Cadbury
Posts: 74
Joined: Thursday Dec 27, 2007 8:24 pm

Re: Changing pre-boil gravity

Post by Cadbury »

Thanks,
So if the measurements were the other way, I would do the same calculation and add some malt. So if I wanted 1.050 and got 1.039 I would just reverse that formula and add the amount of malt needed. Have I got that right?
Cadbury
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warra48
Posts: 2082
Joined: Wednesday Apr 04, 2007 12:45 pm
Location: Corlette NSW

Re: Changing pre-boil gravity

Post by warra48 »

Yep, that's how it works.
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