Availability of nutrients for the plant, depends on pH-level!

pH value
Variations in pH during cultivation will affect the quality of your plants. Low pH levels disturb the uptake of elements such as potassium, calcium, magnesium and molybdenum. Low pH can increase toxicity because some trace elements are absorbed too easily. A pH value that is too high can prevent a plant from absorbing phosphate and trace elements (with the exception of molybdenum.

EC
Electrical Conductivity (EC) is the amount of electrical current water can carry. EC is expressed as milliSiemens per centimeter (mS/cm) at 25C. The electrical conductivity of water is actually a measurement for salinity. Soil with excessively high salinity, or high EC, can prevent efficient nutrient absorption by the plant. Irrigation water with high EC is also unfavorable for usage on plants, because it limits the possibilities of fertilization and it can harm plants.

Water hardness
The simple definition of water hardness is the amount of dissolved calcium and magnesium carbonate ions in the water. Hard water increases the pH in the growing medium. Soft water on the other hand reduces pH in the root environment in case acidifying fertilizers are used. It's essential that growers take measures to improve water quality. Whether the water is hard or soft, ICL Specialty Fertilizers provides expert advice on how to control the quality of your water.