I've read a number of threads concerning this topic, but was hoping someone could chime in and help answer a few questions I still have.
Here's my setup:
15.5gal MLT w/ false bottom
Volume of liquid UNDER the false bottom (i.e. the amount of liquid needed to fill the MLT until it is level with the false bottom) = 11cups (2.75qts)
Volume of liquid in the Deadspace (i.e. the amount of liquid left in the MLT after draining via the diptube) = 1.25cups
The first volume (11cups) is not deadspace because most of it gets transferred to the boil kettle. The 1.25 cups of liquid left behind is liquid from the "deadspace."
Here's my dilemna though.
If I have 20lbs of grain I am mashing at 1.25qts/lb, I would mash with 25qts (6.25gal). BUT if I don't factor the 2.75qts of water that will be under the false bottom, in actuality the grain is sitting in a mash of 1.11qts/lb. That's a bit thicker than the target 1.25qts/lb. Not terrible, but that's for a big grain bill.
But say I have only 12lbs of grain. At 1.25qts/lb, I would mash in with 15qts (3.75gal). BUT if I don't factor the 2.75qts of water that will be under the false bottom, in actuality the grain is sitting in a mash of 1.02qts/lb. That's a pretty thick mash.
By adding 2.75qts to each amount of strike water, the grain will actually be in a mash that has a ratio of 1.25qts/lb. From what I've read, most guys DO factor that extra volume in. That makes sense to me. I want a 1.25qts/lb ratio so I need to make sure that's what I've got in contact with the grain. But I still have questions.
1. Does this change in volume in the MLT have any detrimental effect on the finished beer? A "thicker mash" tends to produce beers with more body while a "thinner mash" tends to produce beers with less (I know this is a simplification).
2. If I factor for the additional 2.75qts under the false bottom, I know the grain is still technically in a 1.25qt/lb mash, but does that extra volume of liquid affect the fermentability/body in the finished beer?
3. I fly sparge but I do NOT recirculate (no pump...yet). So if I simply sparge until I hit my target pre-boil volume, will there be any issue with the "semi-diluted" wort that was in the MLT? That extra 2.75qts of water that was added to the mash will dilute the wort strength a bit, so making higher gravity beers or doing a "no-sparge" could be a little bit more tricky.
Am I seeing this right? I know. I know. Before you say it. RDWHAHB. But I also want to make sure I'm seeing this right. Thanks in advance.