# Water gravity relation

Im messing around with beer smith and it got me stuck on a concept. I made a recipe I havent brewed it i’m just looking how the numbers effect each other.

When i change the final bottleing volume it does not change the % alcohol. This has me confused about how gravity relates to the amount of water.

ah i think i just figured it out… stoopid, stoopid, stoopid. Ive been thinking about this for an hour lol.

Specific gravity measures dissolved solids, a Homogeneous mixture which would be the same regardless of bottleing volume unless additional water was added after fermentation. The losses that occur becuase of wasted wort and trub do not effect gravity and thus do not affect estimated ABV.

Ill post this just incase any other noob has wondered about this or if someone can confirm or crush my new found understanding

What i was thinkin of was yes if you use fermentables to make a 5 gallon batch but use 4 gallons of water you’re wort will be condenced and your gravity will be higher than expected.

I really don’t get that deep when I’m brewing. The depth of my thoughts extend to “Will this taste good?”

The volume that matters is how much volume you have in the kettle after boil. All else being equal, if you boil harder and end up with less wort volume, or add less water to begin with, you will end up with a higher gravity wort.

Once the boil is done, the gravity of the wort is what it is, and any future losses (due to trub, spillage, whatever) just reduce the volume, without changing the potential alcohol.

In beersmith, if you want to play with volume vs gravity, you need to change the batch size, not the bottle volume. If the bottle volume doesn’t match the batch size, beer smith just assumes you lost wort between boiling and bottling for some reason, not that you had less wort to begin with.

Not exactly the same thing but it took me some time to dial in how much volume I needed at the end of the boil to get at least 5 gallons of finished beer. More than I thought is lost to trub in the boil kettle and then trub in my fermentor. For my system I need ~6 gallons at the end of the boil to get ~5.2 gallons of finished beer at the end.

I agree with Nate42’s assesment.

Example:
15lbs of grain. 5 gallons in the fermenter. Gravity 1.052. 8-6pks of beer. 0 waste.

15lbs of grain. 5 gallons in the fermenter. Gravity 1.052. 7-6pks of beer. 72oz of waste.

The only way to change to gravity is to change the starting volume or the gain/fermentables

[quote=“Nighthawk”]I agree with Nate42’s assesment.

Example:
15lbs of grain. 5 gallons in the fermenter. Gravity 1.052. 8-6pks of beer. 0 waste.

15lbs of grain. 5 gallons in the fermenter. Gravity 1.052. 7-6pks of beer. 72oz of waste.

The only way to change to gravity is to change the starting volume or the gain/fermentables[/quote]

I am confused by this. Wouldn’t the volume in the fermenter be less to account for the waste? Otherwise, were is the waste between the fermenter and the bottle?

[quote=“560sdl”]I am confused by this. Wouldn’t the volume in the fermenter be less to account for the waste? Otherwise, were is the waste between the fermenter and the bottle?[/quote]Since the gravity and initial volumes of both batches is the same, the waste must have happened in the transfer from the fermenter to the bottling bucket, through leaving beer in the fermenter or having lots of trub in the fermenter or spilling during the transfer.

[quote=“560sdl”][quote=“Nighthawk”]I agree with Nate42’s assesment.

Example:
15lbs of grain. 5 gallons in the fermenter. Gravity 1.052. 8-6pks of beer. 0 waste.

15lbs of grain. 5 gallons in the fermenter. Gravity 1.052. 7-6pks of beer. 72oz of waste.

The only way to change to gravity is to change the starting volume or the gain/fermentables[/quote]

I am confused by this. Wouldn’t the volume in the fermenter be less to account for the waste? Otherwise, were is the waste between the fermenter and the bottle?[/quote]

The amount that you put in the fermenter is the same in both examples. In the 1st example you bottle everything.

In the second example, you leave 72 oz behind so as not to pick up the extra yeast/hops/trub.

So the number of bottles change, but the gravity stays the same.

Or a different example to have the same number of bottles:

15lbs of grain. 5 gallons in the fermenter. Gravity 1.052. 8-6pks of beer. 0 waste.

17lbs of grain. 5g +72oz in the fermenter. Gravity 1.052. 8-6pkz of beer. 72oz of waste.

Ok, I thought the loss was in the transfer from brew pot to fermenter. Nighthawks adjustments would fix that as well.

The easy way to think about it is if you dry hopped with a goodly amount of whole hops, they absorb a lot of water, so you have less available to bottle, but the ABV is the same as if you hadn’t dry hopped. I learned this painful lesson once with a wet hopped pale ale - a ton of beer was soaked up by the huge pile of dry hops used!