Quarts per Pound

[smyrnaquince]

When a quantity like 1.5 quarts of water per pound of grain is quoted for a mash, is that total water used for the mash or do I have to add in extra water to allow for what will be absorbed by the grains?

 

[jessej122]

I usually add an extra gallon but that's just me and my equipment

 

[stpug]

You would add any "deadspace" volume but otherwise that is the correct ratio - no other adjustments needed. Of course, multiply your poundage by your ratio to get your water volume.

Example)
1 quart deadspace in MLT
12 grainbill at 1.5:1
12*1.5 = 18 quarts
18 qt + 1 qt deadspace = 19 quarts strike water

 

[smyrnaquince]

Thanks, stpug. That makes sense. I'm using a braid, so no dead space. I can just use the ratio directly.

 

[LandoLincoln]

It should be x quarts per pound in the mash, and you don't compensate extra for deadspace or anything else. The whole concept of quarts per pound is the relationship to the amount of water being used during the mashing process, not anything else, so don't compensate for anything else.

Example: if you're shooting for 1.5 quarts per pound in your mash and you have a 10 pound grain bill, you should be using 15 quarts of water in your mash. "But what if I have a .25 gallon deadspace?" That's irrelevant. You're not looking for a 1.5 quarts per pound ratio in your boil kettle.

Let's say you wanted to get 6.5 gallons of wort out of a 10 pound mash and you wanted to have a ratio of 1.5 quarts per gallon. You have a mash tun with a .25 gallon dead space. And you're batch sparging.

One pound of grain absorbs 1 pint of water and there's 8 pints of water in a gallon, so a 10 pound grain bill would absorb and keep about 1.25 gallons.

Mash 15 quarts (3.75 gallons) of water with 10 pounds of grain. Drain the mash tun. That should net you about 2.25 gallons of wort for your first runnings. 3.75 gallons minus 1.25 gallons absorbed by the grain minus .25 gallons left in the deadspace equals 2.25 gallons into your boil kettle. 4.25 gallons still needed.

Sparge with 2.25 gallons of water, and that should net you 2.25 more gallons. Since the dead space was already full of .25 gallons of wort, you don't have to account for it anymore.

And then sparge a second time with 2.25 gallons of water, and stop the sparge when you get to 6.5 gallons in your boil kettle. Some people think it's a waste of time sparging more than once, but I get an extra three percent efficiency when I do a double sparge, so in my opinion I think it's worth it.

 

[stpug]

It should be x quarts per pound in the mash, and you don't compensate extra for deadspace or anything else. The whole concept of quarts per pound is the relationship to the amount of water being used during the mashing process, not anything else, so don't compensate for anything else.

Example: if you're shooting for 1.5 quarts per pound in your mash and you have a 10 pound grain bill, you should be using 15 quarts of water in your mash. "But what if I have a .25 gallon deadspace?" That's irrelevant. You're not looking for a 1.5 quarts per pound ratio in your boil kettle.

I agree with most of what you said, but not the deadspace issue. There are circumstances where the deadspace may be as great as 1+ gallons. Mashing a small grainbill would yield unpredictable results if you did not account for this deadspace, not to mention that you'd be stirring something like mason's mortar with how thick it would be.

Example)
English Mild 5Gallon
7.25 lbs grainbill
1.25:1 ratio
1 gallon deadspace
7.25*1.25 = 9.06 quarts (2.26 gallons)

If I put 2.26 gallons in my MLT I will only have 1.26 gallons above the false bottom for the grain to mix with creating an effective ratio of grist to water of 0.70:1 - a big difference from 1.25:1. So, yes, you DO need to know your deadspace and how you will account for it in certain circumstances.

 

[Gitmoe]

Honestly I didn't read all these long responses but I don't see the grain absorption rate figured into any of the equations. You'll lose .13 gallons per lb of grain to absorption....

10lbs grain x .13 = 1.3 gallons lost to absorption in the mash that won't run out to the kettle. Add that number back into your sparge water to make up the loss.

 

[stpug]

Honestly I didn't read all these long responses but I don't see the grain absorption rate figured into any of the equations. You'll lose .13 gallons per lb of grain to absorption....

10lbs grain x .13 = 1.3 gallons lost to absorption in the mash that won't run out to the kettle. Add that number back into your sparge water to make up the loss.

It's not like this is a 100+ page thread, there are only 6 posts above yours and one is the OPs question. If you take time to read what's already been posted you'll better be able to focus your input around what's already been said. At least you were honest about it

While what you say is true, it doesn't play a factor in initial water:grist ratio that the OP was asking about (i.e. it is already accounted for in the ratio). Like you said, it WILL play a factor during sparging though.

 

[JustLooking]

Dead space is the fluid that your equipment leaves behind after run-off and is separate from grain absorption. I'd always thought that mash thickness is what it is, but this thread has me thinking. What about space under a false bottom? Since there is no grain there should that be taken into consideration in a different way?

 

[smyrnaquince]

I'm the OP. I am now thinking that the water:grain ratio has to do with the concentration of extracted enzymes in the mash and therefore the dead space does not get factored in. (This assumes that the deadspace is small enough that all the grains are submerged.) The deadspace would come into play when calculating the total amount of mash + sparse water needed.

Sound right?

 

[billl]

Obviously, anyone can add however much extra water they want, but.... the term refers only to water per lb grain. Nothing else is taken into account at that step.

That is entirely separate from the idea that not every system will respond to the same mash ratio in the same way. You might well have to thin out your mash due to dead space or a tiny grainbill, but that doesn't change the meaning of 1.5 quarts per lb.

Just think of it this way. If you add 1.5 quarts of water per lb of grain and stir it around it a bucket, it doesn't matter what kind of tun you pour it into, you would always be at 1.5.

 

[acidrain]

I don't agree.
If I didn't add for RIMS tube, hoses, pump and FB space, my grains wouldn't even be covered.
The fact is, as long as the PH is within range, it doesn't matter if you do a full volume mash, 1.25/lb., or somewhere in between.
I mash at 1 gallon per 3 lbs grain, + 1/2 gallon.

 

[billl]

The fact that your system doesn't run well on a particular mash ratio doesn't change the ratio in question. If you add 1 gallon/3lbs +1/2, then if you have a 12 lb grain bill, you are using a mash thickness of 4.5 gallons/12 lbs = 1.5 qt/lb.

Whether that works better for you than 1.33 or 1.25 is a completely different issue.

 

[JustLooking]

It's the ratio of water to grain, but if some of your water is not in contact with grain, I wouldn't think that water should be part of the ratio.

 

[GilSwillBasementBrews]

Just because that water isn't in contact directly with the grains it is in contact with the water that is and the enzymes being leached from the grain into said water are there whether the grains are or aren't. The water to grist ratio is just that x amount of water to a pound of grain. It's not x amount of water to a pound of grain plus whatever you want to add in, rims tube, dead space, purple cows, etc etc etc.

 

[BackAlley]

Honestly I didn't read all these long responses but I don't see the grain absorption rate figured into any of the equations.

It's in the third response.

 

[LandoLincoln]

I agree with most of what you said, but not the deadspace issue. There are circumstances where the deadspace may be as great as 1+ gallons. Mashing a small grainbill would yield unpredictable results if you did not account for this deadspace, not to mention that you'd be stirring something like mason's mortar with how thick it would be.

Example)
English Mild 5Gallon
7.25 lbs grainbill
1.25:1 ratio
1 gallon deadspace
7.25*1.25 = 9.06 quarts (2.26 gallons)

If I put 2.26 gallons in my MLT I will only have 1.26 gallons above the false bottom for the grain to mix with creating an effective ratio of grist to water of 0.70:1 - a big difference from 1.25:1. So, yes, you DO need to know your deadspace and how you will account for it in certain circumstances.

Yes, you do have to account for deadspace in relation to your pre-boil volume, but the deadspace isn't relevant to the quarts-to-pounds ratio. If you have a 10 gallon mash tun with a 3 gallon deadspace, you think that you should add an extra three gallons to the mash? That would severely affect the emzymatic action of the mash. Are you saying that the volume of water below your false bottom isn't contributing anything to the mash, emzyme-wise? I would disagree.

On the other hand, in our homebrewing scales, adding a half of a quart to a mash to compensate for mash tun deadspace isn't going to seriously throw off the ratio all that much anyway. Is there REALLY that much of a difference between a 1.5 quarts per pound mash versus a 1.62 quarts per pound mash? Probably not.

 

[RoadKing]

If you have a 10 gallon mash tun with a 3 gallon deadspace, you think that you should add an extra three gallons to the mash? That would severely affect the emzymatic action of the mash. Are you saying that the volume of water below your false bottom isn't contributing anything to the mash, emzyme-wise? I would disagree.

THIS... I have a 2 gallon space under my false bottom. I like the mash thickness of 1.33 Qts. per Lb. so I fill the MLT just to the false bottom then figure for 1.33 Qts. Per Lb. For an average 11 Gallon batch with 16 Lbs. of grain it ends up being around 1.67 Qts. per Lb. I only make 10 gallon batches but if I were to do an average ABV 5 gallon batch, I think the mash might be too thin at that ratio.

 

[JustLooking]

Just because that water isn't in contact directly with the grains it is in contact with the water that is and the enzymes being leached from the grain into said water are there whether the grains are or aren't.

My thinking is that the thin portion of the mash below a false bottom or in a RIMS tube contains enzymes, but not starches. As long as there are plenty of enzymes in the thick mash, you will get conversion there, but the "thickness" of the mash is only measured where liquid and grain are together.

 

[GilSwillBasementBrews]

My thinking is that the thin portion of the mash below a false bottom or in a RIMS tube contains enzymes, but not starches. As long as there are plenty of enzymes in the thick mash, you will get conversion there, but the "thickness" of the mash is only measured where liquid and grain are together.

I don't see it that way. If there are enzymes in the water due to being in contact with the water in contact with the grains. Then the water is also picking up the starches as well as the enzymes. At least that is my opinion. Doesn't really matter one way or the other we are all making beer and as long as we are content with the way we are doing things does it really matter if x amount of water should be used over y amount of water. And who's to say which way is preferable. The old addage of ask a question to 5 brewers get 10 answers. Etc etc etc.