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Old 09-21-2012, 01:33 PM   #1
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Default Does 1-1.25 qt./lb. rule account for grain absorption?

I've read conflicting (or ambiguous) advice from various sources, so I'm hoping someone here can clear this up for me. I'm planning on doing my first partial mash this weekend, and I'm trying to figure out how much strike water to start with. The recipe uses 5 lbs. of grain, and I plan to use the higher end of the 1-1.25 qt./lb. ratio to have a "runnier" mash and reduce the risk of a stuck sparge.

So that means I need 6.25 qt. of strike water. However, I'll lose 2 qts. to grain absorption (0.1 gal/lb, right?), which means my first runnings will only be 4.25 qts. Following conventional wisdom that says my batch sparge volume should be equal to my first runnings, I'll also sparge with 4.25 qts.

My question is, should I add that 0.1 gal/qt. of grain absorption on top of my 1.25 * lb. of grain calculation, or is it already accounted for? I mean, since 1.25 * 5 lb. of grain gives me 6.25 qt., and I know my grains will absorb 2 qts, should I be striking with 8.25 qts. instead? Then my first runnings (and sparge) will be 6.25 qt. instead of 4.25 qt. What are you supposed to do here?

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Old 09-21-2012, 01:40 PM   #2
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I've read conflicting (or ambiguous) advice from various sources, so I'm hoping someone here can clear this up for me. I'm planning on doing my first partial mash this weekend, and I'm trying to figure out how much strike water to start with. The recipe uses 5 lbs. of grain, and I plan to use the higher end of the 1-1.25 qt./lb. ratio to have a "runnier" mash and reduce the risk of a stuck sparge.

So that means I need 6.25 qt. of strike water. However, I'll lose 2 qts. to grain absorption (0.1 gal/lb, right?), which means my first runnings will only be 4.25 qts. Following conventional wisdom that says my batch sparge volume should be equal to my first runnings, I'll also sparge with 4.25 qts.

My question is, should I add that 0.1 gal/qt. of grain absorption on top of my 1.25 * lb. of grain calculation, or is it already accounted for? I mean, since 1.25 * 5 lb. of grain gives me 6.25 qt., and I know my grains will absorb 2 qts, should I be striking with 8.25 qts. instead? Then my first runnings (and sparge) will be 6.25 qt. instead of 4.25 qt. What are you supposed to do here?
The "rule" isn't 1-1.25 quarts- it's more like 1.25- 2 quarts water per pound. I like a slightly thinner mash, and usually go with 1.5 quarts/pound. But either way is fine.

Anyway, say you use 1.25 quarts/pound. Yes, the grain will absorb about .1 gallon/pound. So, if you have 6.25 quarts you strike with, you'll get out about a gallon of first runnings. Then you sparge with up to 2 quarts per pound, to get up to your boil volume.

In this case, I'd probably mash in with 7.5 quarts (1.5 quarts/pound), as then get 1.35 gallons of first runnings and sparge with the same amount.

I hope that helps!
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Old 09-21-2012, 01:45 PM   #3
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The mash ratios already account for grain absorption.

For a partial mash though, go ahead and use a higher ratio if you want. eg 1.5, 1.75 etc. All of those will work as long as you don't go crazy (eg gallons per lb or something). The exact volumes are really only important when you are trying to hit an exact volume for your full boil. Since you are going to be adding water and extract anyway, anything in the ballpark will work just fine.

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Old 09-21-2012, 01:51 PM   #4
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Thanks for the replies, guys, that helps a lot, but brings up another question. Doesn't using a higher ratio compromise extraction efficiency? Given that I'm planning on batch sparging, which isn't the most efficient way to sparge to begin with, wouldn't I want to use a lower mash ratio to try and recover as much efficiency as possible from the mash, knowing I'm going to sacrifice some during sparging? Or should I have simply increased my grain amounts by 10-15% from the outset to account for the efficiency loss of both batch sparging and a higher-ratio mash?

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Old 09-21-2012, 02:11 PM   #5
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Batch sparging is only slightly less efficient. In fact, i average 80-81% consistently with a single batch sparge AND a thin mash. I actually don't want it to be any more efficient.

So, i wouldnt worry about efficiency as a number to start with. its more important to have a CONSISTENT efficiency, and then tweak accordingly (ie, add more grain, try a thinner/thicker mash, more/less sparge water). But, once you've established consistency, make sure you only 'tweak' one thing at a time, so you can ensure you know what the effect is. you know, the 'scientific process' and so such...

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Old 09-21-2012, 02:16 PM   #6
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The difference in efficiency is negligible - it really comes down to personal preference and what works best on your system. I personally like to mash thin so that I have to sparge less.

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Old 09-21-2012, 02:47 PM   #7
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" Doesn't using a higher ratio compromise extraction efficiency?"

No. It generally improves efficiency as long as you can still sparge with enough water and hit your volumes. It is a very common technique to "mash out" - ie add hot water at the end of the mash (before draining or sparging) to heat it up and thin it out.

Sugar (or anything else in solution) moves from areas of high concentration (the grain) to low concentration (the water). Adding more water moves out more sugar. That is the whole idea behind sparging. In all-grain brewing, the limiting factor is the total amount of wort you want to collect. eg 7 gallons. You could get more total sugar out if you collected 8 gallons, but then it would be diluted with an extra gallon of water you don't really want. (You could boil that down and evaporate that gallon before you started your real boil. That is sometimes done with really high gravity beers.)

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Old 09-21-2012, 05:13 PM   #8
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That is sometimes done with really high gravity beers.
Sometimes it's the only way to get decent efficiency with large grain bills.
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Old 09-21-2012, 05:33 PM   #9
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Originally Posted by kombat View Post
Thanks for the replies, guys, that helps a lot, but brings up another question. Doesn't using a higher ratio compromise extraction efficiency? Given that I'm planning on batch sparging, which isn't the most efficient way to sparge to begin with, wouldn't I want to use a lower mash ratio to try and recover as much efficiency as possible from the mash, knowing I'm going to sacrifice some during sparging? Or should I have simply increased my grain amounts by 10-15% from the outset to account for the efficiency loss of both batch sparging and a higher-ratio mash?
I saw my efficiency go up about 5 points when I increased from 1.25 to 1.75 qt./lb.

I've batch sparged 427 batches as of yesterday and I got 89% efficiency yesterday. I mashed with 1.75 qt./lb. and sparged with about 4.25 gal. for a 5.5 gal. batch. Batch sparging is not necessarily less efficient than fly sparging.
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Old 09-21-2012, 06:42 PM   #10
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" Doesn't using a higher ratio compromise extraction efficiency?"
I agree with Bill, but there can be a case where a thinner mash could reduce efficiency. If the brewer uses a high alkalinity water and increases the volume of water in the mash, the amount of alkalinity added via that extra water can overwhelm the grain acidity and raise the mash pH. If that pH rise is taken far enough, the extraction and conversion of starches can be reduced.

Considering that alkaline tap water is prevalent for most of the US and many brewers do not adjust their water chemistry, it is conceivable that a loss of efficiency may be observed by some brewers when using a thinner mash. Brewers that know how to adjust their water are probably not going to have an efficiency loss and as pointed out by many in this thread, they are likely to gain efficiency with a thinner mash.
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