Any nutritional value that we add to water is known as EC+ and should be added to the water’s residual EC.
Tap water can contain sodium and chloride, for example, which have an EC value but no nutritional value for plants.įertiliser is made up of nutritional salts, of course. Water that contains mineral salts has an EC but the presence of EC alone does not necessarily indicate that the water contains nutritional salts that will help plants. Fortunately, there is a fixed calculation for the relationship between all these units, which is given in the table below. This is done by converting the EC into a value based on the ions contained in the solution. In North America, conductivity is converted into a count of the ions in the water using parts per million (which can also be converted into units including mg/l etc.).
The mS/cm unit is generally used in Europe as a guide to the concentration of nutrients in water. EC unitsĮlectrical conductivity can be expressed using a number of different units, but the typical unit is siemens per meter2 per mole (S/m2/mole) or millisiemens per centimetre (mS/cm). All conductivity measurements are directly affected by temperature and this must be allowed for when making them. When we add nutrients (salts) to water, we increase the molar conductive potential for current through water and thus increase the EC value (or CF = EC*10). Salty seawater, on the other hand, is a much better conductor. Pure water is a very poor conductor of electricity, which is why an EC meter will read 0.0 in rainwater, reverse osmosis water or de-mineralized water. It is these ions that transport the electrons.īy the same token, the concentration of ions in the water also determines the number of electrons that can travel from one electrode to the other: the higher the concentration of ions, the greater the flow of electrons. Electrons are able to flow through the water from one set of electrodes to another not because of the water molecules themselves, but because of the ions dissolved in the water. This is known as molar conductivity (electrolytic conductivity) and is measured in siemens (S). It is important for growers to have a good understanding of what EC is all about and why it matters.īy Pieter Klaassen CANNA research Electrical ConductivityĪn EC meter measures the potential for an electrical current to be transported through water. Although most growers are used to measuring the amount of feed that they give in ounces per gallon, grams per litre, or some other unit of measurement, EC goes a little further than this. EC stands for electrical conductivity, which is the potential of any material to conduct electricity.