HY-GEN® pH DOWN contains 85% food grade Orthophosphoric acid and will to LOWER the pH when added to your growing system. It’s recommended that you prepare your nutrient solution first and allow it to equilibrate; this can take up to 60 minutes depending on the size of your tank. Always add the required amount of pH DOWN to a small separate container of water and mix well before adding to your nutrient tank. WHEN TO USE Use pH DOWN every time your pH is too high. Adjust the pH only after tap water or additives are added to your tank. Once adjusted mix well and allow 30-60 minutes before re-testing and adjusting.