I was curious as to what water profile folks have been using for the "Rocky Mountain Spring Water" in Golden, CO. I did a cursory search on the web and found the 2015 Water Quality Report for Golden, CO but was surprised to see that among the dissolved ions typically reported, they did not include measures for Ca, Mg, or Bicarbonate. Here's the 2015 report (mean values):
Alkalinity, ppm = 39.25
Hardness, ppm = 108.0
pH = 8.39
Sodium (Na), ppm = 24.68
Potassium (K), ppm = 2.675
Chloride (Cl), ppm = 26.45
Sulfate (SO4), ppm = 80.05
Bicarbonate (HCO3), ppm = not reported (46.8 estimated)
Carbonate (CO3), ppm = not reported (0.5 estimated)
Calcium (Ca), ppm = not reported (38.9 estimated)
Magnesium (Mg), ppm = not reported (2.6 estimated)
Here was my methodology for determining the estimated values:
Bicarbonate/Carbonate: Used Bru'n Water v1.18 (2016), Tab 1. Water Report Input, Alkalinity Conversion Calculator. Entered Total Alkalinity (39.25) and pH (8.39); calculator then estimated Bicarbonate as 46.8, Carbonate as 0.5. These were then entered in the Water Report Input section of Bru'n Water v1.18 (along with all other reported ion measures).
Calcium (upper limit): Used Bru'n Water v1.18 (2016), Tab 1. Water Report Input, Ion Concentration Conversion Calculator. Converted Total Hardness (108.0 ppm) to US Hardness (6.30 grains/gallon), then entered US Hardness; calculator estimated upper limit of Ca as 43.2 ppm (which assumed 0.0 ppm Mg). I then entered a temporary value of 43.2 ppm Ca to the Water Report Input section of Bru'n Water v1.18.
Magnesium (upper limit): Used Bru'n Water v1.18 (2016), Tab 1. Water Report Input, now with the temporary Ca value of 43.2 ppm entered. I then entered a random high value for Mg, paying attention to the "Water Report is unbalanced. Check your inputs" warning. I progressively decreased my guesses for Mg until the "Water Report is unbalanced" warning disappeared (which occurred at 5.2 ppm Mg, while using the temporary value of 43.2 ppm Ca). Thus, I assumed 5.2 ppm Mg was the upper limit of Mg; recall from the previous step that the lower limit of Mg was assumed to be 0.0 ppm.
Ca/Mg Final Estimates: Using 5.2 ppm as my upper limit of Mg, I calculated Ca using [(Ca/20) + (Mg/12.1)] * 50 = Total Hardness (p. 158 of Palmer's "How to Brew" 2006), using 108.0 for Total Hardness and 5.2 for Mg and solving for Ca. This yielded 34.6 ppm Ca (as a lower limit of Ca) when assuming 5.2 ppm Mg. I then simply took the average values between the upper/lower limits of Ca & Mg, calculated from the previous steps. Mg = (0.0 + 5.2)/2 = 2.6 ppm Mg. Ca = (34.6 + 43.2)/2 = 38.9 ppm Ca. These new Ca/Mg values were then entered in Bru'n Water v1.18 (2016), Tab 1. Water Report Input, to confirm that the water report was balanced (i.e. no errors flagged). Success!
If anyone has a more complete water report that cites the actual values for Mg, Ca, & HCO3 I'd certainly be interested to see it - if for no other reason than to see how close my estimates were. Hope this information is of some value to folks... Cheers!