Question on Mash Water Quantity (need advice on this one) - Home Brew Forums

 Home Brew Forums > Question on Mash Water Quantity (need advice on this one)

10-10-2012, 01:53 PM   #1
rich
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Apr 2010
New York
Posts: 13

Okay Boys (and gals) - here's my issue. It's positive, but I want to get it right.

I built a 1.5 barrel system that I basically assembled, and tested in parts, but am just approaching the firt batch. I haven't mashed in yet. I had a pretty cool false bottom made that resides about 2.5 inches above the bottom of the tun. Now that's a fair amount of space under there when considering it's a larger vessel - that bottom section probably can hold about 3 to 4 gallons of water (I'm estimating).

When I calculate my mash water, I'm using the formula of 1.5 quarts of water per lb of grain. Now in the past, when brewing 5 gallon batches, the false bottom that I used was small, and there was only a small void under the false bottom from the mash.

Let's say I calculate my total mash water - for one recipe as an example, I am looking at 34 gallons at a 1.5 quart ratio. It will give me a mash that's not too thick, but not diluted - right in the middle. But if the grains are being pushed up by 2.5 inches by the false bottom (or to put it on the same terms, but reversed - if the water is being drawn away from the grains into the void), I would think this would result is a thicker mash, which I am not sure whether or not would alter the final outcome. I understand that a water ratio of 1.25 could be used for a sweeter, maltier outcome. If the grains were now concentrated into a smaller area - I would think it would create for a thicker mash..... and I would be losing control over starch conversion process.

QUESTION IN A NUTSHELL: In your expert opinions, does the water volume that will accumulate within the void under the false bottom need to be added to the total mash water that will be used when doughing in? Will that void need to be filled first, just to maintain a medium thick mash?

Should I be calculating the mash water like this:
1.5 quarts water x total pounds of grain + water accumulating in void under mash tun.

10-10-2012, 11:28 PM   #2
Francus

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Aug 2012
Charlotte, NC
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5 gallons in a 1.5 barrel system or 47.25 gallons or 10.5%. I'd say up the mash ratio to 1.75 quarts and call it a day. Worst case you end up with a little dryer beer. If you get a beer that seems a bit dry for your liking on a regular basis, drop it back down again. Either way, I'm sure it will taste great and the average non-brewer wouldn't be able to tell the beer was 10.5% dryer than you intended.

Just my .02.

10-10-2012, 11:36 PM   #3
Yooper
Ale's What Cures You!

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How are you recirculating? If you've got an efficient recirculating system, I wouldn't take the deadspace into account at all.
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10-10-2012, 11:37 PM   #4
Francus

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...and I'm jealous

10-11-2012, 12:56 AM   #5
rich
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Apr 2010
New York
Posts: 13

Yooper,

I'm coming from a home brewer's background, so I am recirculating I guess the way I used to - draw some off, pour it over the top. There's going to be a lot of mistakes I'm sure on Friday. What would constitute an efficient recirculating system? I could pump it back over the top, or just manually draw from the valve.

You wouldn't take that space into account? How come? I'm just trying to understand all this myself.

10-11-2012, 01:01 AM   #6
helibrewer

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Santa Rosa, CA
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If you are continuously recirculating, such as a RIMs or HERMs, then all the water essentially contacts the grain throughout the mash process so you would not have to account for deadspace.
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10-11-2012, 01:28 AM   #7
Yooper
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Quote:
 Originally Posted by helibrewer If you are continuously recirculating, such as a RIMs or HERMs, then all the water essentially contacts the grain throughout the mash process so you would not have to account for deadspace.
Right! And with a 1.5 barrel system, you're obviously going to recirculate. So, you shouldn't need to account for deadspace.
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10-11-2012, 10:21 AM   #8
mabrungard

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Since the chemistry of the water does affect the chemistry of the mash, you do have to include the entire volume of water in your calculations. Sooner or later, that deadspace water will be incorporated into the wort and affect the quality, quantity, and chemistry of the wort. Count everything in the tun.
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10-11-2012, 12:14 PM   #9
Yooper
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Quote:
 Originally Posted by mabrungard Since the chemistry of the water does affect the chemistry of the mash, you do have to include the entire volume of water in your calculations. Sooner or later, that deadspace water will be incorporated into the wort and affect the quality, quantity, and chemistry of the wort. Count everything in the tun.
I hope I didn't sound like I said not to account for the water underneath the false bottom. I meant to absolutely "count" that water, but not to worry about it, as when you recirculate, the entire mash is totally incorporated. It's not just "sitting" under the false bottom doing nothing- it is part of the pH of the mash, the enzymatic activity, etc- just like the water above the false bottom.
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10-11-2012, 04:15 PM   #10
rich
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Apr 2010
New York
Posts: 13

I appreciate the feedback. I am not using a Herms or Rims system. My system is basically a homebrew system on steroids (built it like that). My mash tun is fully insulated, and holds it's temps pretty well (was surprised how well during tests). I'll be recirculating manually, old school homebrew Vorlauf style.

I hear you about all of the grains and water coming together - my main issue is the thickness of the mash itself that will be impacted by the grains being held 2.5" above the floor of the kettle, and some of the water drawing down into that area.

With the feedback you guys gave me, tonight I'm going to measure how much water actually falls into that void, then when I calculate my mash water, I'm going to just add it onto the end number - just so that the mash is a good consistency. I have heard people say that brewing on small systems then going to a bigger system often doesn't translate into the same outcomes. I'm figuring this is one of the reasons.

On that note, if anyone has any other suggestions for areas that I may get jammed up over while trying to apply my homebrew background to a bigger system, I'm all ears. I think this covers a major base, but I'm not sure if I'm missing anything else.