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Robusto
03-26-2012, 01:27 PM
Hi all,
I’m just wondering if anyone has a Step Feeding calculator or knows how to crunch the numbers to determine how to adjust the OG to get an accurate ABV once fermentation stops. So, for instance, take the following scenario:

I start with an OG of 1.2 and the yeast take it down to 1.05 and then I add more honey to bring the gravity up to 1.10.
The yeast take it back down to 1.05 and I add more honey to bring the SG back to 1.10.
I then let the yeast take the SG down to where I want it at, say, 1.01, and then stop fermentation.

Now I know that my example may not me realistic, but I wanted to use round numbers to make the math easy.

thanks

YogiBearMead726
03-26-2012, 05:32 PM
I could be wrong, but using your numbers I get 1.200-1.050=1.150. 1.150+(1.100-1.050)=1.200. 1.200+(1.100-1.010)=1.290.

So, an adjusted OG of 1.290. Did you get another number?

machalel
03-26-2012, 06:30 PM
I would have though that your "total" OG is 1.20 plus two increases of 0.05 = 1.30?

Then your total drop is 1.30 - 1.01 = 0.29

YogiBearMead726
03-26-2012, 06:57 PM
I would have though that your "total" OG is 1.20 plus two increases of 0.05 = 1.30?

Then your total drop is 1.30 - 1.01 = 0.29

Ah, sounds right. I was thinking about it too much and solved for points dropped...good catch. :)

TAKeyser
03-26-2012, 08:26 PM
What yeast are you using because if I'm reading this right we're talking 40% abv and everything is going to poop out long before that. Shit my hydrometer only goes up to 1.17

skunkboy
03-26-2012, 10:17 PM
misplaced a decimal point? new math? http://www.youtube.com/watch?v=Vetg7vWitTU&feature=related

Robusto
03-27-2012, 10:41 AM
I would have though that your "total" OG is 1.20 plus two increases of 0.05 = 1.30? Then your total drop is 1.30 - 1.01 = 0.29

Aha... Ok. I didn’t know that you could use “simple” math- I thought that there would be some sort of compounding effect (like bank interest), but I guess if you just calculate “points” in vs points out you get your number. Pretty cool.


What yeast are you using because if I'm reading this right we're talking 40% abv and everything is going to poop out long before that. Shit my hydrometer only goes up to 1.17

TAK-
I know that the numbers are ridiculous, but I just used round numbers to make the math easy.

YogiBearMead726
03-27-2012, 10:47 AM
<snip>...Now I know that my example may not me realistic, but I wanted to use round numbers to make the math easy.

thanks


What yeast are you using because if I'm reading this right we're talking 40% abv and everything is going to poop out long before that. Shit my hydrometer only goes up to 1.17

I believe this was just a hypothetical situation using round numbers so that he could get a feel for calculating the step feeding.

Edit: Doh...beat me to it. :p

TAKeyser
03-27-2012, 11:16 AM
TAK-
I know that the numbers are ridiculous, but I just used round numbers to make the math easy.

OK, no one before me said anything and I was just like "am I reading these numbers wrong". 1.1 is a round number that could produce actual results :)

huesmann
03-31-2012, 09:44 AM
By my calcs, you would have (for example) 5 gallons of must with 28.18 lb of honey in your original 1.200 must. You would then ferment down to 1.050 and add 9.27 lb of honey for a total volume of 5.79 gallons to get back to 1.100. You would then ferment down to 1.050 and add 10.73 lb of honey to get back to 1.100, for a total volume of 6.70 gallons. This is an equivalent OG of 1.255. Fermenting down to a FG of 1.010 gives you an ABV around 33%, depending which formula you use. Of course, getting a 1.200 must to take off would be a bit of a trick.