Base Water for Water Profile

The Water Profile Tool requires entry of the Amount of Base Water to be able to calculate any mineral additions to base water to achieve target water profile.  Should the amount of Base Water be equal to Total Water Needed (Mash Water + Sparge Water) or just Mash Water? Or to say it another way, should I make mineral adjustments to just the mash water or to the mash and sparge water? 

I had the exact same question and am lucky enough to have ajdelange's water profile tool as well to do comparisons. What I have come to the conclusion of based on punching numbers int both ez_watercalc v3 and beersmith is that it is only for adjusting the base mash profile not the sparge water. When calculating additions to the sparge water it puts the ions way over target. So my conclusion is only adjust your mash not your sparge though if anyone here with more expierence know something different please advise.

just re read your question one amendum would be step 1 - put total amount mash and sparge into the base profile gal space  step 2 - select your base profile step 3- select your target water profile . step 4 - hit calcualte best addition button step 5 - only adjust your mash water not your sparge based on the additon reccomendation. i hope this answered your question better.

aschecte, Are you saying that if total water needed = 18 gal (mash water =10 gal and sparge = 8 gal), I should add enough minerals based on 18 gal to hit my target profile, but then only add these minerals to the mashtun??  Wouldn't this overdo the amt of minerals to add to the 8 gal of mash water.

The way I understand it yes. It will add too much minerals to the mash water but you need to look at the overall which is adding the additional untreated sparge water which dilutes the ion content of the mash water.