Does anyone know how to make hard water with a hardness of 200+ ppm in terms of $\ce{CaCO3}$?
I live in Seattle and we have very soft water and we need hard water for testing purposes. Obviously you cannot dissolve $\ce{CaCO3}$ in water. I've read many "recipes" even ones that claimed you can dissolve $\ce{CaCO3}$ with a soda stream pop maker. Best I could do was a 60 ppm.
I've tried baking soda and Epsom salt and was able to make 130 ppm.
I've tried $\ce{HCl}$ to dissolve it in water, but the resulting pH was not suitable and if I tried to raise the pH, the $\ce{CaCO3}$ precipitated back out of the water.
I'm at a loss on a "recipe" that actually works. Am I trying to replicate the possible? Any ideas?