
02252013, 03:12 AM

#1

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Megapot Dead Space Under False Bottom


I have a question about the 10 gallon Megapot and it's false bottom as used for mashing a 5.5 gallon brew. Sorry if this is a ridiculously obvious question. Just hoping to settle all doubts. Any and all advice appreciated!
The space below the false bottom holds about 2 gallons of water/wort.
 should this quantity of water be included or not in the formula of 1.52.0 quarts of water per pound of grain? (i.e. a 12 lb grain bill uses 4.5 gallons of water at 1.5qt/lb.) Should I really be adding another 2 gallons of water to reach the bottom of the false bottom? (6.5 gallons total?!)
if so, it seems that there will there be less sparge water used to reach about 7 gallons for a preboil level? I know the grain absorbs a lot but....
if not, then using only 4.5 gallons of water, only 2.5 gallons will be in contact with the grain during mash
Thanks in advance



02252013, 03:19 AM

#2

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You need to find out what the dead space is. What doesn't drain out when filled



02252013, 03:33 AM

#3

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Additionally with 2 gallons under the false bottom you might need to mash a little thicker to ensure that all the grains get wet. A 4.5 gallon strike with 2 gallons under the false bottom could equal a lot of dry grains.



02252013, 03:38 AM

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I have the same pot, so I know exactly what you're talking about.
Within reason, it doesn't matter much, since the water/grist ratio isn't really that critical. But you're right that if you go too thick on your mash you won't cover the grain.
I do a single batch sparge so I follow denny's advice of aiming for equal runnings from the mash and the sparge. So let's say I'm shooting for a preboil volume of 7 gallons, which means I'm shooting for 3.5 gallons of first runnings. Say my grain bill is 14.5 lbs, so I add 14.5*0.125=1.8 to account for grain absorption. Finally, I add the dead space of my kettle (i.e., how much water is left behind after I drain), which for me is about half a gallon. So I end up with 3.5+1.8+0.5=5.8 gallons of strike water. Then the sparge water calculation is easy  just half the preboil volume, or 3.5 gallons.
Hope that helps!



02252013, 11:19 PM

#5

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Quote:
Originally Posted by tophmck
I have the same pot, so I know exactly what you're talking about.
Within reason, it doesn't matter much, since the water/grist ratio isn't really that critical. But you're right that if you go too thick on your mash you won't cover the grain.
I do a single batch sparge so I follow denny's advice of aiming for equal runnings from the mash and the sparge. So let's say I'm shooting for a preboil volume of 7 gallons, which means I'm shooting for 3.5 gallons of first runnings. Say my grain bill is 14.5 lbs, so I add 14.5*0.125=1.8 to account for grain absorption. Finally, I add the dead space of my kettle (i.e., how much water is left behind after I drain), which for me is about half a gallon. So I end up with 3.5+1.8+0.5=5.8 gallons of strike water. Then the sparge water calculation is easy  just half the preboil volume, or 3.5 gallons.
Hope that helps!

+1
I have a similar system, and this is more or less how I do it from a volume standpoint.



02262013, 01:02 PM

#6

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Quote:
Originally Posted by Nitcomb
I have a question about the 10 gallon Megapot and it's false bottom as used for mashing a 5.5 gallon brew. Sorry if this is a ridiculously obvious question. Just hoping to settle all doubts. Any and all advice appreciated!
The space below the false bottom holds about 2 gallons of water/wort.
 should this quantity of water be included or not in the formula of 1.52.0 quarts of water per pound of grain? (i.e. a 12 lb grain bill uses 4.5 gallons of water at 1.5qt/lb.) Should I really be adding another 2 gallons of water to reach the bottom of the false bottom? (6.5 gallons total?!)
if so, it seems that there will there be less sparge water used to reach about 7 gallons for a preboil level? I know the grain absorbs a lot but....
if not, then using only 4.5 gallons of water, only 2.5 gallons will be in contact with the grain during mash
Thanks in advance

I have a 15 gal MoreBeer kettle as my MLT and it has 2.5 gal of water under the false bottom of which 1/2 gal is left behind after the MLT it completed drained, not including water absorbed by the grain. I determine my mash volume based on 1.5gal per quart + 1/2 gal per Beersmith 2.0 software. I fill my MLT until my false bottom is just submerged, then I add the strike water volume I had previously determined. I have a HERMS so the entire volume of liquid comes in contact with the grain several times over. I consistently get 87% mash efficiency.





