Keeping the nutrient levels up in your hydroponic nutrient solution is an important part of growing large, healthy vegetables and flowers. There are a number of manufacturers of nutrient meters. Although the exact procedure will vary slightly for each manufacturer's meter, the overall process is similar for each meter. Testing your nutrient solution is not difficult if you use a good, calibration-free meter.
Place the sensor head in the hydroponic solution to bring it to the same temperature as the hydroponic system.
Remove the sensor from the solution for a few seconds and place it back in the solution to take the initial reading.
Read the conductivity value on the wand of the meter. If the lights are flashing between two values, they indicate a measurement between the two values. For example, if the lights are flashing between 4 and 6, it indicates a measured value of 5. If your meter has a digital readout, simply read the displayed numbers.
Allow the unit to switch off automatically to take another reading. In most cases, a second reading can validate an unexpected reading.
Use an EC conversion chart for your meter to establish nutrient parts per million in your hydroponic solution.