It still doesn't make sense to me.
I have a media which i am preparing be adding the known amount of all the salts one after another.
If you know amount of salts added, water hardness masurement doesn't make sense - what you will get is the concentrations of ions put into the solution +/- experimental error. Analysis is just a waste of time.
If you are after equlibrium concentrations, analysis of total concentrations (as in the case of water hardness) will not give you any answer. Equlibrium concentrations can be measured using specroscopic or potentiometric techniques mainly.