somewhat new to AG, newbie question

[jameyg]

I don't understand something on this Promash report:

========================================================
Pre-Boil Amounts
Evaporation Rate: 15.00 Percent Per Hour
Pre-Boil Wort Size: 5.88 Gal
Pre-Boil Gravity: 1.042 SG

Mash Schedule
Mash Name: Single Infusion Mash
Total Grain Lbs: 9.00
Total Water Qts: 10.35 Before Additional Infusions
Total Water Gal: 2.59 Before Additional Infusions


Ratio
Single Infusion 5 60 153 153 Infuse 167 10.35 1.15
Mashout 1 10 170 170 Infuse 210 5.16 1.72

Total Water Qts: 15.51 After Additional Infusions
Total Water Gal: 3.88 After Additional Infusions
Total Mash Volume Gal: 4.60 After Additional Infusions
=======================================================

Ok so if I'm trying to make a 5 gallon batch, and my "pre-boil" wort size is 5.88 gallons (to account for evaporation, i assume) then why at the bottom is the "Total Water Gal" equal to 3.88? Where is this other two gallons coming from? I can't imagine I'd mash/mashout, add this to boil pot, then just dump 2 gallons of regular water into the pot to make 5.88 gallons. What am I missing? Also, what is "Total Mash Volume Gal?" Thank you guys in advance!

 

[IamNash]

My understanding from using Promash is that the rest would be sparge water. I tried out promash and was confused by it not actually saying this outright, and also not providing the volume needed to sparge with, since the grain will absorb some. I tried out BeerSmith and its pretty explicit about how much sparge water you need to achieve your pre-boil volume. My first all grain batch, I just measured how much wort I got after mashout, and subtracted that volume from my boil size to calculate sparge volume, but its nice to know it ahead of time so you can heat only the amount you need.

 

[jameyg]

Ahhhh, that makes sense, thanks!