Water chemistry while using distilled for sparging

[acarter5251]

Hi,

I'm planning on brewing a beer this weekend using the Denver, CO water profile in Beersmith.  I planned to build the water from distilled water for my mash (need about 5.3 gallons) and using distilled water with no adjustments for the remaining 3.4 gallons of sparge water.

To use the Water Profile Tool, should I use 5.3 gallons for the base water and include the 3.4 gallons of distilled water as the dilution volume?  I have done this and it gives me recommended additions, but the final values are off from the desired values.

Desired: 31.5 Ca, 8.5 Mg, 21.4 Na, 50.8 SO4, 23.5 Cl, 104.0 HCO3
Actual: 21.0 Ca, 7.7 Mg, 16.1 Na, 30.5 SO4, 13.4 Cl, 62.5 HCO3

Thanks in advance!

 

[BeerSmith]

BeerSmith is doing a "best fit" which is technically a least squares method to come as close as it can.  It minimizes the square of the distance from the target water and mixed water.  That's about as close as you can get realistically using additions with your base water.

Brad