In some circumstances, such as when water is of poor quality, or high temperatures increase transpiration, pH and conductivity levels can rise sharply.

In order to compensate for this, the pH and conductivity levels of the nutrient solution should be adjusted to a slightly lower level than that which is recommended for the type of plant/stage of growth. This will ensure that conditions are nearer to the plants ideal, as illustrated below. How often you will need to check and readjust the solution will depend on the rate and magnitude of the rise.

In this example, the nutrient solution is checked and corrected to pH 6 every three days. During this three day period, the pH may rise one point to pH 7, which will result in a significant change of conditions for the plant.



However, if the pH of the solution is checked and adjusted every three days to pH 5.5, over the same period the conditions in the nutrient solution will not deviate so far from the ideal for the plant, even though the pH rises by the same amount.