dunleav1 wrote:Sulfate, SO4-S 6 ppm
The clue is in that -S. "SO4-S" is read "sulfate as sulfur" which means that instead of listing the actual mass of the sulfate they list the mass of the sulfur in it. Note that the same idea is used with nitrate which is listed as NO3-N. That means it's the mass of the nitrogen in the nitrate that they are giving you - not the mass of the nitrate ion. I'm guessing they do this because their background seems to be in agriculture where they like to list the amount of nitrogen, phosophorous, sulfur, etc. applied per acre irrespective of what salt it's bound up in. SO4 -S 6 ppm means that SO4, as we usually think of it, i.e. the mass of the sulfate ions per liter, is actually 18.