Don't despair, go to a pond store and get the chemical test kits. The paper ones suck. No r/o water does not come out to 7 or 6. I have r/o water and it comes out the same as my tap, 8.1. GH nutes do drop your ph a little, but it depends what you started with. I've been using GH nutes and I have to adjust my ph with vinegar every day to bring it back down. I'm not sure what other people do, this is my first hydro grow. My soil plants are great, but my hydro plants have had slimy roots, twice and are growing at a snail's pace.