I also have well water with a watersoftner in the pumphouse and then for drinking water (kitchen only) we have another filtering system. I have read many different opinions regarding well water, softner water and regular tap water and I can see why people have issues with these sources of water. I have decided to build a rain water capture system to be used in my green house. If I could afford it I would build a huge underground sistern, but I think my only option will be to have several rain barrels on the side of the house closest to the greenhouse. My goal is to have it completed by the end of summer in time for the fall rain season.
As for water testing, as a newbie, of course I went crazy and tested all my water sources when I got my new toy
I now only test my PH twice a week with the drops. I haven't yet purchased a PPM meter because I only have the one system up and going. I kind of agree with GPSFrontier that if I follow the directions and watch my plants there really shouldn't be a need. I will probably purchase one when I get the greenhouse up and going just because I like new toys and am somewhat of a control freak.