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 Home Brew Forums > Calculating strike/sparge water

03-08-2013, 07:45 PM   #1
ziggityz
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 Calculating strike/sparge water

I have read and read and read about calculating strike/sparge water amounts. I usually start with a 7 gallon pre-boil amount and usually gets me down to 5-5 1/2 gallons after a 60 minute boil. I have yet to brew and AG beer but have some extract under my belt. I used brew target to run a few recipes through to see exactly how much water I will need for each. My grain bill is 8.75 lb. I calculated 1.25 qt/lb strike water and got 2.734 gallons of water for the strike water. If the run-off for the sweet wort after the hour long rest is supposed to be equal to the sparge run-off there is no way I am going to get 3.5 gallons from the initial run off. I'll end up with more of a ratio of 2 gallons + 5 gallons. Am I calculating something wrong???

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03-08-2013, 08:07 PM   #2
Conan
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Kinda. Your first runnings will be about 1.5 gallons I'll estimate, based on your numbers below. After you collect your first volume, subtract that from your preboil (7-1.5= 5.5). Divide that amount be the number of sparges. If you're fly sparging, simply use 5.5 gallons in the sparge. If you batch sparge and are doing two, equal vol. sparges you would use (5.5/2= 2.25) per sparge.
I haven't accounted for losses to tun deadspace with any of these calculations. If you've pretested your system and know you won't be able to drain .25 gal after each water addition, add that number on to your sparge volume. So, on a single sparge you'd need 5.75 gallons. For a double batch you'd use 2.5 gallons each.

My fly sparge assumptions may be wrong because I only batch. If so, please correct me. Kyle

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03-08-2013, 08:08 PM   #3
Hammy71
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Your sparge amount is almost always going to be larger than your strike amounts. I'm going to assume you are Batch sparging. Mash with 1.25 qt/#. After an hour recirculate to clear and drain the first runnings. Measure the first runnings (marked buckets work great and are close enough). Subtract that amount from your pre-boil volume. That number is the amount of sparge water you will need. I divide my number in half to make two equal sparge amounts (I think that is where you confusion may be). Using this method you will always end up with the perfect amount of sweet wort to match you pre-boil amount. Hope that helps. I use this calculator to determine my strike water volumes and temps.

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03-08-2013, 08:23 PM   #4
GrogNerd
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Quote:

you only need to account for the deadspace during mash in, not the sparge. once you drain the first runnings, the deadspace is still in there. add your 5.5 gallons in one or two sparges, you'll get 5.5 out
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03-08-2013, 11:01 PM   #5
ziggityz
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Thanks for the info, but my concern was that if each run of wort should be equal... how is that ever possible to get 3.5 gallons for the first run and 3.5 gallons after the sparge (batch sparge in my case) or 3 and 4...something close

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03-09-2013, 12:48 AM   #6
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You can't do it while holding everything fixed. The numbers you're trying to hit are not independent.

Think of it this way. For a given batch size, you have the following variables:
- amount (pounds) of grain
- amount (quarts) of wort
- mash ratio (quarts water per pound of grain)
- sparge "schedule"

Assuming you know your efficiency and you have a target OG to hit, the first two are fixed. You will extract something proportional to the efficiency times the amount of grain in gravity points. You then need a particular amount of total water to hit a pre-boil volume such that your post-boil gravity will be correct, after accounting for various losses. These numbers are now fixed. You *must* have that quantity of grain and that total quantity of water or you will be changing the recipe.

So you now need to design your mash and sparge schedule. If you want a particular mash thickness, this completely determines your initial strike volume because the amount of grain is fixed. That then determines how much sparge water you will need because the total water is fixed.

So something's got to give. You can't choose all these variables. If you want to balance your mash and sparge volumes, then you have to adjust your mash thickness.

That's a bit of a simplification because I assumed that your efficiency is fixed. In truth, these other choices will impact your efficiency in some brewery-dependent way. You have to determine what this is mostly from experience---pick a thickness or sparge schedule, find out what sort of efficiency you get. Tweak your recipe until you're content.

I guess there is one option, which is probably not what you have in mind, but it does technically solve your problem. You could mash with your desired ratio, sparge with an equal volume of water, and then make up your desired volume by adding water without sparging. I don't know why you'd want to do this unless you're worried about excessive sparging causing a problem. Otherwise you might as well sparge out whatever traces of sugar you can.

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03-09-2013, 01:29 AM   #7
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So complicated...
Mash at 1.25 - 1.5 qts. per lb of grain. A good "in between" calculation is 1 gallon per 3 lbs of grain.
Mash at your recipe temp, and collect the wort.
Measure the volume, and figure out how much more you need for your pre-boil volume.
This is the amount of sparge needed. Divide it up, or just do one sparge... whatever.
There is no set ratio of mash and sparge.

The only rule to sparging is, you don't want to gather less than 1.010 gravity. If the sparge water isn't gathering sugars, stop. It can strip tannins.

One question though, is that actually a recipe, or are you just using it as an example? 8.75 lbs of grain is extremely light for a 5.5 gallon batch of all-grain.

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03-09-2013, 03:03 AM   #8
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Quote:
 Originally Posted by GrogNerd you only need to account for the deadspace during mash in, not the sparge. once you drain the first runnings, the deadspace is still in there. add your 5.5 gallons in one or two sparges, you'll get 5.5 out
Thanks for catching that, you're right. As I typed it I thought something didn't sound right, but drone-typed anyway and hit send.

After glossing through all the info we've all laid out here, just listen to acidrain's synopsis. It's dead-on. And to answer your question in post 5, no each running does not need to be equal. Get what you can from the first runnings and make up your required volume with subsequent sparges. Kyle
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03-09-2013, 12:03 PM   #9
Hammy71
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Quote:
 Originally Posted by ziggityz Thanks for the info, but my concern was that if each run of wort should be equal... how is that ever possible to get 3.5 gallons for the first run and 3.5 gallons after the sparge (batch sparge in my case) or 3 and 4...something close
There is no need for them to be equal. The first runnings and your sparge amounts do not need to be equal. Not sure where you heard that.....
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03-09-2013, 06:11 PM   #10
ziggityz
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I watched the northern brewer all grain brewing video with john palmer... thats where I heard for better efficiency they should be equal

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