« on: April 24, 2015, 11:31:12 AM »
For simplicity, I have gone to standard equal water volumes then adjusted post mash by adding sparge water to the mash before Vorlauf based on the amount of grain and assuming a .125 gallon per pound of grain absorption to get to a "close enough" to equal runoff in the two runs. Maybe unnecessary per Denny, but done by choice since a routine is helpful...ymmv.
If I have a monster grain bill, I will improvise and do a batch/fly-like sparge by starting the run and adding the rest of the water water slowly to the second sparge as it is draining, before it gets to a "dry grain bed". A rarity but it worked fine enough and pH didn't suffer with all of the water being treated per Brunwater.
I have a three keg system with an elevated HLT, so I can do this relatively easily without a pump and cracking the HLT drain valve slightly open, rather than full bore.
At the BIAB level, I have not really worried about it and just mash pretty thin. (Though my BIAB brewing is usually limited to mid-winter in house brewing when SWAMBO allows.)