quick question about ppm. my ro water is 70-80 ppm at stock, once ive added a little superthrive and 1/4 nuts its on 160. now ive read elsewhere you shud aim for 650-750. how am i supposed to reach that, and if i shhudnt, what is a gd number. i only fed 1/4 strength. before reverse osmosis my water is at 340ppm. plz help im realy confused. thankyou