Connoisseur Grow Part A (4-0-0) will keep the pH of your nutrient solution stable within a range optimal for nutrient uptake for one week. For optimal results, we recommend using reverse osmosis (RO) water or water up to approximately 100 ppm (EC 160 S/cm). This product is specially designed for use with diverse hydroponic growing media, including peat, rockwool, and expanded clay pellets, and all continuous liquid-feed growing systems and since it also contains our proprietary pH Perfect A® Technology, eliminating the need for pH and ppm metering, pH Perfect Connoisseur Grow Part A is an invaluable asset to your growroom.