When the nutrient solution is made up, it may not be at the ideal level of pH 6, particularly if you are using tap water, so you will need to correct it.

This is easily done by adding a ‘pH solution’ to the nutrient solution. ‘PH up’ will make the solution more alkaline and will raise the pH level, ‘pH down’ will make the solution more acidic and will lower the pH level. You will only need to use a few drops of pH solution per litre, depending on the quality of the water.

The quality of the water used to make up the nutrient solution will have a bearing on the pH level. Most of the U.K. has hard water, which has pH levels above pH 6, so you will need to bring down the pH level of your nutrient solution. Soft water areas have a low pH, so you will need to raise the pH level.