To maximize plant growth, the pH of your nutrients should be slightly acidic. Experienced growers consider the ideal pH for most crops to fall between 5.5 and 6.5. Users of General Hydroponics nutrient products generally do not experience problems maintaining the proper pH range because our formulas are pH buffered.
However, some important exceptions do exist. Acid content can reach unacceptable levels when nutrient solutions are mixed with poor quality water, or when pH unstable media – such as rock wool or gravel products – are used, or when high plant growth rates destabilize the nutrient mix due to rapid nutrient absorption by the crop.
pH Up: This base solution is formulated using potassium hydroxide and potassium carbonate. Add a little at a time when your nutrient pH is too low in order to raise the pH to the proper level.
When adjusting pH, start out with one ml per gallon. Wait 15-30 minutes, and test your water again. Frequently you will only need 1-2 ml per gallon of water. You may need to use more if you have hard water.