If you are using the flora series I believe you should be fine. (3 part brown micro, green veg, and pink bloom). You may need to watch your dissolved mineral levels like calcium and magnesium. They could be high or low and you should adjust the formula accordingly. It depends on your area's yearly water report, which should be posted online. Not only that, the GH Flora series has a specially formulated alternative for hard water. The micro bottle, I believe, is the one that is different, but then again they all could have the hard water version.(grow, micro, and bloom) I have 300ppm well water and have no problems, other than pH adjustment down to a suitable level. In my case I'm 300 ppm, pH around 7.8-8.2. I use the vial pH method because the probes are expensive to replace. I used the GH flora series with municipal tap water in the past with success, but now I use the dyna-gro line with some other stuff for as needed situations/problems. The well water has been great.