Plants grown hydroponically depend on a nutrient solution for all the elements that they use to grow and thrive. But just as a well-mixed nutrient solution gives life to a plant, a solution that is too strong can kill a plant. In order to determine if your solution is too strong, you must test the solution's nutrient content. The proper way to do this is to determine both the electrical conductivity and pH of the solution.
Select an EC meter that is appropriate for your style of hydroponic system. The EC meter measures the electrical conductivity of the liquid solution, which is an indicator of the amount of nutrients in the solution. An EC meter with a metal probe that can be inserted into the water or into soil is appropriate for a hydroponic system.
Remove the cover of the EC meter from the probe. Turn the EC meter on and insert the probe into your hydroponic chamber.
Write down the EC reading and compare it with the optimal EC readings for your particular hydroponic plants on the EC chart.
Dip the end of a pH testing strip into the nutrient solution and let the strip absorb the solution. Compare the color of the pH strip against the results on the indicator chart to find out the pH of the solution.
Determine how much nutrient is being absorbed into the plant based on the solution's pH. A plant will only absorb half of the nutrients available in the nutrient solution in pH that is acidic below 6.5 or above 7.5. Then use your EC chart reading to determine the nutrient concentration for the plant you are growing.