Moderator moved/merged this post into this topic. It was originally posted in Global Customized Water at home
brianl wrote:I find it interesting that the author says calcium carbonate is confusing/misleading because it might be magnesium but in the summary table of the measurements, uses the term calcium carbonate.
It can be confusing unless you keep in mind that water treatment chemists use a convention of "as CaCO3" when reporting. They take whatever they are reporting and convert it to a chemical equivalent amount of CaCO3. So the water here has 6 ppm Mg++, and zero Ca++, but converted to CaCO3 equivalents the 6ppm Mg++ comes out to 25 ppm total hardness "as calcium carbonate" that you see in that summary table.
brianl wrote: So the total TDS of your solution, as read by a TDS meter
That 'as read by a TDS meter' is an Important distinction, and interesting in this case. For typical drinking water, you can use a standard NaCl-calibrated TDS meter and it will give you numbers that are in the ballpark of the actual TDS. You would expect the TDS to be in the neighborhood of 100 mg/l, because you dissolved 70 mg of bicarbonate and 30 mg of epsom salt in the water. But the TDS meter might read closer to half that because the conductivities of NaHCO3 and of MgSO4 solutions are lower than that of NaCl.