Question about calculating mash thickness

[Seedly]

I have a 10 gallon pot that I plan on using for an E-BIAB vessel. It has a nice false bottom that was made for it that I was going to use to keep the bag off the element. My concern is that the false bottom sits at about the 2 gallon mark, leaving 2 gallons below the grain.

When calculating my mash thickness, would I need to exclude those 2 gallons? I.E. I have 13 lbs of grain that i want to mash at 1.25qts/gal. To do this, I would need 6 gallons in my pot (2 below the false bottom and 4 for the grains to swim in).

Am I thinking correctly on this?

 

[GilSwillBasementBrews]

You would want to figure out your qts/LB ratio then add that in addition to what's under your false bottom.

 

[Bobby_M]

Well if you're doing a traditional no-sparge BIAB process, you're going to be mashing at Preboil volume + (pounds of grain x .1 gallon) anyway.