Mash thickness: with or without the external, under false bottom volume ?

[brewman !]

Lets say I am mashing 8 pounds of grain and my system has an "external" volume of 1 gallon. (hoses, under the false bottom, etc.)

Lets say I want a mash thickness of 1.5 quarts per pound.

Should I strive to have 1.5 quarts per pound in contact with the grain ? ie 8 pounds x 1.5 = 12 quarts = 3 gallons. Plus 1 gallon that isn't in contact = 4 gallons total ?

Or should the entire mash water volume be 1.5 quarts per pound, ie 8 pounds x 1.5 = 12 quarts = 3 gallons. 1 gallon will be under the false bottom and in the hoses, so 2 gallons will be in contact with the grain bed.

What matters: the ratio of water to grain in the bed or the ratio of water to grain in the entire system ?

Thanks

 

[Rev2010]

Yes, you should calculate to have all the grain contact the water, unless of course you have a recirculating system then no it would just be the quarts per pound x grain bill. If not recirculating then yeah it would be as you said 1.5 quarts x grain bill + space underneath. In my tun there's .39 gallon under the false bottom not contacting the grain so I just do my usual math then add the .39 to it.


Rev.

 

[brewman !]

Yes, you should calculate to have all the grain contact the water, unless of course you have a recirculating system then no it would just be the quarts per pound x grain bill. If not recirculating then yeah it would be as you said 1.5 quarts x grain bill + space underneath. In my tun there's .39 gallon under the false bottom not contacting the grain so I just do my usual math then add the .39 to it.

Huh ? My system recirculates.

 

[Rev2010]

Huh ? My system recirculates.

Then you would only do desired quarts per pound. Recirculating exposes the grain to all the available strike water. I couldn't determine from your initial post if you are indeed recirculating or not.


Rev.

 

[doug293cz]

You need enough water in contact with the grain so that you can stir without too much trouble at mash in (unless you plan to underlet and not stir), and also to have all of the grain below the liquid level during the mash. There is nothing "magic" about any particular mash thickness. I don't even think about mash thickness when calculating volumes (other than a max allowable thickness), but rather how to try to get close to equal run-off volumes to get optimal lauter efficiency.

Brew on