Water pH is a mathematical term to denote degrees of acidity or alkalinity and is expressed by a series of positive numbers between 0 and 14 with 7 being neutral. Zero being very acidic and 14 highly alkaline. Water pH can be measured by a hand held pH meter operated by a small battery.
The pH of the water has a significant impact on the availability of certain elements in the water. Water pH should be between 5.8 and 6.8. Values higher or lower than 5.8 and 6.8 results in either precipitation or renders some elements unavailable to the plants for uptake.
If the pH of the water is above 6.8, nitric acid, phosphoric acid or sulpheric acid can be used to decrease the pH to the desired level. pH lower than 5.8 must be increased to the desired level with potassium hydroxide (KOH), sodium hydroxide (NaOH) or magnesium hydroxide (MgOH2).