For proper plant growth two elements are important to consider: the PH and EC. Plants prefer water quality, so when there is excess of calcium or magnesium (hard water) plants can be damaged because they prefer a more acidic habitat. The acidity is expressed by pH, taking into account the level of ions in the water. The lower the pH level, the higher the acidity level. A soil with a pH of 7 is neutral, is acidic below and alkaline above. For most plants a desirable level is between 5.5 and 6.0 and stable. If this value varies the amount of food consumed by the plant also varies and this may be shown in the appearance of the plants.