Question on EZ Water Calculator 2.0

I have never used the EZ water calculator and am trying to use it for the first time for a brew I am going to do today.

My basic question is this. According to the instructions, sparge additions are not to be added to the mash but to the boil.

Am I understanding this correctly that any additions that are labeled as sparge additions are to be added after the mash is complete and the wort is in the kettle?

Does this mean that my sparge what is untreated? I thought the sparge pH was important with respect to leaching tannins and haze materials?

In other words, I will require 8.72 total gallons. 5.21G is for the mash and 3.51G is slated for the sparge. Do need to segregate my water, add my mash mineral additions to the 5.21G I will mash with. And then use the 3.51 sparge gallons untreated? I then add the rest of the mineral additions to the boil kettle?

I am just confused as to why I would not treat my sparge water as I always thought the pH of the sparge was also crucial.

Thanks for your help.

If the sparge water pH is high, it can raise your mash pH potentially past 6 where you risk tannin extraction if the water is much above 170. You can use distilled or RO and it shouldn't cause the mash pH to raise past 6, but you'll need to account for that water being RO or distilled in your calculations. Some people do treat their sparge water with acid to lower the pH to the safe range but depending on the acid used it could affect the beer flavor (lactic acid is tangy for example).

"sparge" additions go in the boil kettle because they are pretty much just for flavor modification, it is too late for them to affect pH for mash enzymes. Additionally some water salts dissolve poorly in water, and less poorly but not perfectly in the mash as well. If your sparge water is treated with salts that do not dissolve well, you could try keeping it stirred up.

Certain minerals, notably chalk, require low pH to dissolve. If you add it to your HLT, it will never make it into your mash tun.