EC Meters for Nutrient Solutions

Optimum nutrient uptake through exact determination of the EC value

Next to the pH value, the EC value is the most important measurement parameter in nutrient solution. EC stands for Electric Conductivity and indicates the electrical conductivity of a substance, in this case of the solution. The EC value thus also provides information about the dissolved solids concentration in the water. Especially in hydroponic or aeroponic systems, but also when growing in coco or rockwool, the exact determination of the EC value is crucial for the success of the grow.
The EC value is usually measured in microsiemens (µS/cm) or millisiemens (mS/cm), where 1000 microsiemens equals one millisiemens. In summary tables, EC is often expressed in mS/cm, sometimes in the abbreviated form mS.

Daily checking of the EC value

The salinity of the water used affects the electrical conductivity (EC). Thus, saline water with 50 mS/cm über a significantly higher conductivity than tap water with about 0.5 mS/cm. Distilled or demineralized water has the lowest electrical conductivity of only 20 µS/cm. The ideal starting value for water as the basis for nutrient solutions is 0.2-0.4 mS/cm and thus often below the EC value of the available tap water. If the value of the tap water is even higher, it is particularly important to reduce the EC value accordingly. For example, with a reverse osmosis system to ensure the optimal supply of nutrients to the plants.
If the EC value is too high, there is a danger of salinization or overfertilization of the soil. In this case, the plant can not absorb further nutrients. On the other hand, if the EC value of the nutrient solution is set too low, there is a danger of underfertilization.
If the grow is done in soil, it acts as a buffer and can store minerals. When growing on nutrient-free coco or in aeroponic systems, this buffering does not exist. With this in mind, regular measurement of the EC value is recommended when growing on soil. With Coco or other grow media, however, it is essential!
Thus, the EC value is usually with advancing growth of the plants increased, as they can then absorb much more nutrients - the value should not exceed 2.0, however.

Determining the EC value correctly

With a properly calibrated EC meter, determining the EC value is relatively straightforward. The probe of the EC meter is held in the nutrient solution and the device shows the EC value on the display only a short time later.
Note: all components of the Dünger should be added to the nutrient solution before measurement and this should be stirred well. Depending on the measurement, the EC value must either be reduced by the addition of neutral water, or corrected upwards by the careful addition of fertilizer.
To determine the EC value, there are devices for continuous measurement in the nutrient solution or hand-held devices with which the measurement is easily possible at any time, depending on the requirements.

Regularly calibrate the EC meter

Before the first measurement, the EC meter must be calibrated. Subsequently, the EC meter must be calibrated approximately every two weeks, otherwise precise measurement results cannot be guaranteed and the device will operate increasingly inaccurately. Even after regular cleaning, the EC meter must be calibrated again. Usually, a calibration fluid is needed to calibrate the EC meter. An exception is, for example, the Bluelab Truncheon, which does not need to be calibrated and is correspondingly easy to use.
Equally important for präzise measurement results is the regular ßige cleaning of the EC meter. Ideally, the EC meter should be cleaned after each use and stored in distilled water. Special cleaning fluids for EC meters make this task easier.

Conclusion

The regular monitoring of the EC value provides much better information about the nutrient supply of the plants and thus ensures a healthier plant growth and correspondingly better yields.