pH measurement and control

To ensure the long-term stability of nutrient solutions, it is important to maintain the pH between 5.0 and 6.5. This helps ensure all nutrients are available for root up-take. It also minimizes the risk of plumbing blockages.

What is pH?

pH measures the concentration of hydrogen ion (H+) or acidity in a liquid. The pH values of most aqueous solutions, such as drinking waters, have pH values of around 6 to 8. The more acidic the water the lower the pH. Conversely, the more alkaline the solution the higher the pH.

The pH scale is logarithmic, which means that each 1 unit variation in pH represents a 10 fold change in the hydrogen ion concentration. For example, water with a pH of 4.0 is 100 times more acidic than one of pH 6.0.

This article discusses the following topics:

-  Optimum pH of nutrient solutions
-  Adjusting nutrient pH
-  Measuring pH with 'indicators'
-  Measuring pH with pH Meters
-  Calibrating pH meters
-  pH meter maintenance and accuracy problems
-  Buying a pH meter