hi guys & gals, my question is. iv'e got a wilma system when i make up a new nutrient solution, if say i want a ec of 1.5, and my tap water ec is 0.5, do i add the 0.5 to the 1.5 ec and end up with an ec of 2.0 or include it in the 0.5 to make a total of 1.5 ec. just need this clearing up as not sure ty for your help
