EZ Water Calculator - ppm calculations accurate?

[TheWulf]

I've been attempting to add calculations for Potassium Chloride and total Potassium ppm to the EZ Water Calculator and I've been using the existing calculations on the spreadsheet as a reference.

Doing this I came across some an odd result: the existing calculations don't line up with what I would expect.

Let's take the Magnesium PPM as an example. For the sake of simplicity, let's also assume that we're starting with 100% RO water.

- 1ppm is defined as 1mg / L
- In MgSO4, 20.192% of the weight is Mg (https://www.convertunits.com/molarmass/MgSO4)
- Therefore, 100mg of MgSO4 in 1L of water = 100 * 0.20192 / 1 = ~20ppm of Mg
- The EZ water spreadsheet shows a value of 9 ppm. The existing weight multiplication constant works out to 0.0919855 / L. (0.0246 / gal)

Any thoughts on the discrepancy? Am I calculating this incorrectly or is there an error on the spreadsheet? Values for other minerals seem to have a similar discrepancy.

cc @-TH-

 

[TheWulf]

The solution in case someone else looks this up: most of these compounds are actually hydrates despite how they're named on the spreadsheet, likely for simplicity.

https://chemistry.boisestate.edu/richardbanks/inorganic/common_names.htm