If there is a problem with your hydroponic nutrient solution, it is typically that the pH of the water in the solution is out of balance. Plants need a neutral pH (measured as 7 on a scale of 1 to 14) in order to absorb all the elements in the nutrient solution. Lower pH readings indicate that the solution is acidic in nature, while a higher pH may indicate that the hydroponic solution is alkaline. Regular care of the water to keep the pH neutral will help the plant utilize nutrients present in the soil efficiently.
Several factors can affect the pH of a nutrient solution. Adding nutrients to the water can lower the pH of the water. In addition to this, as plant roots sit in a nutrient solution, the plants themselves can gradually lower the pH of the nutrient solution as they absorb hydrogen from the air and water for photosynthesis. In order to keep plants healthy, you must check the pH of the nutrient solution and re-balance the solution periodically.
There are several ways to test the pH of a nutrient solution, but using a pH testing kit, such as the kind found at a pool or aquarium supply store, can give you an accurate reading of your pH. To use a testing kit of this kind, place a small amount of nutrient solution in the testing kit, you can add a small amount of pH testing chemical. The chemical will change the nutrient solution's color. The shade of color that the solution turns is an indicator of the pH of the nutrient solution. Other methods of testing the pH include dipping a pH strip into the nutrient solution or dipping the probe of a calibrated pH testing meter into the nutrient solution.
The pH of a nutrient solution can be re-balanced by adding alkaline or acidic substances to the nutrient solution to raise or lower the pH into the neutral ranges. Safe chemicals that can be used to balance pH include phosphoric acid to lower the pH and potassium hydroxide to raise it. This process can be automated through the use of a hydroponics controller.