Say goodbye to nutrient lockout and hello to heavier harvests. Our scientists engineered pH-Up with potassium hydroxide and pH-Down with Phosphoric Acid, so you can easily achieve the ideal pH levels for optimal nutrient absorption. We’ve developed these highly stable buffers to give you precise control over your pH, even after dilution or adjustments between reservoir changes. Recalibrate pH levels with maximum buffers Highly concentrated formulas for longer use Nutrient Solutions: Mix a new réservoir weekly. Coco: Daily. Other Substrates: 2-4 times/week as necessary. Use small amounts when adjusting the nutrient solution to affect the pH level, as required. Use to maintain the optimum pH level of 5.5 to 5.8 for hydroponics and 6.2 to 6.3 for sphagnum moss and plants in containers. For best results, check the pH level daily. pH-Up & pH-Down is specially designed for use with diverse hydroponic growing media and all continuous liquid-feed growing systems such as aeroponics, drip irrigation and emitters, NFT, flood and drain, and deep water culture.