To maximize plant growth, the pH content of your nutrients should be slightly acidic.
Experienced growers consider the ideal pH for most crops to fall between 5.5 and 6.5.
Acid content can reach unacceptable levels for several reasons.
Among them are poor quality water and pH imbalances resulting from the use of unstable growing mediums.
Also high plant growth rates can destabilize the nutrient mix due to rapid nutrient absorption by the crop.
General Hydroponics pH Up is formulated using Potassium Hydroxide and Potassium Carbonate.
Add a little at a time if your nutrient pH is too low in order to raise the pH to the proper level.