Testing 1, 2, 3!
- Describe what “TDS” measures and why it’s important
- Perform pH and EC tests on hydroponic solution
But once you understand the indicators of health – or in some cases the imbalance – you can more effectively manage your hydroponic system. The two primary measurements you will test are pH and EC. pH measures the acidity of the solution and determines how effectively your plants will be able to interact with the nutrients available to them. An optimal pH range for most greens is between 5.5 – 6.5 in general. EC measures the salts in the solution which indicates the amount of nutrients in it. Shoot for an EC measurement between 1.2 – 2.0 in general.
It may take some practice, but you’ll dial in your system and gain a better understanding of just how to affect the changes to pH and EC needed.
Teach the Teacher
Tools & Materials
- pH / EC meter
- Paper & pencil
- pH Down
- pH - acidity
- EC - measure of salts
- TDS - total dissolved solids
Introduction (10 minutes)
Begin the lesson by explaining the two measurements: pH and EC. Describe how those measurements are taken and how they can be manipulated with fertilizers, acids, and base. Explain why it is important to keep these two measurements at an optimal level for plant health.
Activity (20 minutes)
Using the pH / EC meter, have the Students take measurements in each hydroponic system for pH, EC, and temperature. Record the data for each system. Make any adjustments that are required but be certain not to increase pH by more than (.5) in a given day to avoid shocking the plants.
Show the Students how to clean and store the equipment. Have them help after the first time.
Discussion (10 minutes)
How much did the measurement change from our last test? What do you think would happen if the EC dropped or increased too much? What about the pH?
Assessment (5 minutes)
Use the following questions to assess the Students before and after the lesson. Tally the responses of the group in the Assessment Tracking Log for comparison:
- By a show of hands, how many of you have ever tested water before?
- Now that you’ve tested the solution in our hydroponic system, how many of you think you could do it on your own?