yeah you have hard water but not all that bad, i suggest using cal-mag from any brand of nutrients. heres the problem, i actually read a article on this in maximum yield magazine. the cal-mag molecule from your tap water is too large and it is very immobile. Its size prevents it from being absorbed by the roots. These large cal-mag molecules then start to collect and create nutrient lock out where your plant has difficulties absorbing nutrients. Cal-mag by say botanicare, supplies your plant with a smaller more useable form of cal-mag. Calcium and magnesium are important to the function of nutrient absorbtion. i have the same problem only my ppm is a lot higher in my area. RO systems call for the same cal-mag product since your water source is stripped of all minerals and nutrients. so either way id suggest buying some. i use botanicares cal-mag and it work. hope it helps and i hope im not all over the place