Author Topic: When calculating "mash thickness", should I include all the wort?  (Read 1280 times)

Offline wuertele

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I asked this question on another thread, but nobody answered it, so I guess it was too far off topic:

When calculating "mash thickness", should I include all the wort in the dead space?  Or just what is in contact with the grain?

My MLT has a false bottom, and I have quite a bit of wort in the recirculation plumbing at any given time.  In fact, I have wort sitting about an inch above the grain bed that doesn't contact the mash until it drains down into it.

When I calculate mash thickness, should I include *all* my wort (i.e. the volume of my strike water), or just the wort that is in contact with the grains?

If it is just the wort in contact with the grains, I would have to subtract out 2 gallons from my false bottom, a gallon or more for my plumbing, and about a gallon for the wort abobve the top surface of the grain.
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Offline a10t2

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Re: When calculating "mash thickness", should I include all the wort?
« Reply #1 on: March 19, 2011, 03:35:36 PM »
If I can answer your question with a question, why do you need to know the mash thickness precisely enough that that would make a difference? Although if you really do have 2 gal under the false bottom, that is quite significant. Was that a typo, or is this a 1 bbl system or something?

I'd use the full volume. The enzymes don't know or care how far they are from the nearest bit of endosperm. And if you're using the liquor:grist ratio to calculate infusion temperatures, you'll need to take all the water into account.
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Offline wuertele

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Re: When calculating "mash thickness", should I include all the wort?
« Reply #2 on: March 19, 2011, 03:50:13 PM »
If I can answer your question with a question, why do you need to know the mash thickness precisely enough that that would make a difference? Although if you really do have 2 gal under the false bottom, that is quite significant. Was that a typo, or is this a 1 bbl system or something?
  Not a typo.  I mash in a 15 gallon kettle from B3 that came with a false bottom.  I measured the liquid in the false bottom, it is exactly 2 gallons.  Also, I have all 1" diameter plumbing through my RIMS system.  I haven't calculated how much fits in there, but I would be surprised if it were less than a gallon.

I'd use the full volume. The enzymes don't know or care how far they are from the nearest bit of endosperm. And if you're using the liquor:grist ratio to calculate infusion temperatures, you'll need to take all the water into account.
I thought that mash thickness was all about how far the enzymes were from the nearest bit of endosperm.  Isn't that what determines how active they are?

What if I route my RIMS system through a 10 gallon grant, and continuously cycle my entire wort (mash volume + sparge volume)?  Would that count as a super-thin mash?
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Offline a10t2

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Re: When calculating "mash thickness", should I include all the wort?
« Reply #3 on: March 19, 2011, 08:17:51 PM »
I thought that mash thickness was all about how far the enzymes were from the nearest bit of endosperm.  Isn't that what determines how active they are?

Not until you get to an extremely thin mash (like 4 qt/lb or more). Once the starches are solubilized, they'll diffuse throughout the sparge.

What if I route my RIMS system through a 10 gallon grant, and continuously cycle my entire wort (mash volume + sparge volume)?  Would that count as a super-thin mash?

You'd basically be doing a no-sparge mash, which would be thinner than if you were sparging, but I wouldn't call it super thin. Your efficiency will take a small hit, but lots of people brew that way.

1" ID tubing will hold 1 gal per 6 ft, BTW.
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Offline tschmidlin

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Re: When calculating "mash thickness", should I include all the wort?
« Reply #4 on: March 19, 2011, 11:38:43 PM »
I ignore the water beneath the false bottom when I'm figuring out my mash thickness, otherwise for 5 gallon batches of small beer I would have virtually no water to mix with the grains.
Tom Schmidlin

Offline hopfenundmalz

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Re: When calculating "mash thickness", should I include all the wort?
« Reply #5 on: March 20, 2011, 07:56:18 AM »
The mash thickness that I calculate is for the part above the false bottom in my kettle.  If I draw off from the bottom, it runs clear for some time, so that is just water down there for the most part.

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Offline mabrungard

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Re: When calculating "mash thickness", should I include all the wort?
« Reply #6 on: March 20, 2011, 05:30:53 PM »
In terms of the mash chemistry, all the water within the tun should be included in the water to grist ratio.  As highlighted in Bru'n Water, the grist provides a finite and limited amount of acidity and the mash water provides the alkalinity to moderate the mash pH.  Since the total amount of alkalinity is dependent upon the total water volume, it makes sense to include the total water volume.   

The volume under the false bottom should eventually be recirculated during the mash.  I personally recirculate that volume right off the bat since I sure don't want a slug of water sitting below the screen that hasn't been infused with the starches, sugars, and enzymes.
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