I looking for find explain for the concentraion in second table.

what I mean for example:

the amount used from Ca(NO3)2.4H2O equal 1003 g/1000L.

and the concentration for Ca in the second table (170 mg/L)

If I assume according to atomic weight"

164.1 Ca(NO3)2.4H2O have 40 Ca

and 1003 Ca(NO3)2.4H2O have X

Then X= 1003* 40/164.1

x=244 mg/L

Can any one inform me from where 170 of Ca come??