How to use, calibrate and store pH and EC meters

Understanding and managing pH and EC is key to growing healthy cannabis plants.

pH is a measure of how acidic or alkaline a solution is, and it determines how well the plant can absorb nutrients from water and the growing medium. Even if nutrients are present, the plant cannot absorb them efficiently if the pH is outside the optimal range.

EC (electrical conductivity) measures the concentration of nutrients (salts) in the solution or substrate. This can help prevent under- or over-fertilization.

Measuring pH and EC gives you control over the root zone and helps you identify problems before they become visible in the leaves. It isn’t always necessary, but it can make a big difference depending on the substrate you’re using.

You can measure pH using simple test strips or other basic methods, and there are also more advanced tools available.

For home growers who want the most reliable and consistent results, this guide focuses on how to measure pH and EC/TDS using handheld meters. These devices offer the best balance of accuracy, ease of use, and practicality for everyday cannabis cultivation.

pH and EC target values

For peat and soil:

Irrigation with a pH between 6.0 and 6.5 is usually optimal. EC is less critical here unless problems arise.

In peat-based soils, pH and EC values ​​are usually buffered and more stable, so many growers don’t need to constantly measure.

For coco and hydroponics:

Irrigation with a pH between 5.8 and 6.2. EC values ​​depend heavily on the growth phase and the fertilizer used, so you should always use the manufacturer’s fertilization schedule as a reference.

In coco, hydroponics, or other soilless substrates, these values ​​fluctuate much more. Monitoring is crucial to avoid nutrient lockouts or deficiencies.

About the meters

A reliable, mid-range meter, regularly calibrated, is a worthwhile investment for healthy plants.

Very inexpensive pH and EC meters are often less accurate and lose calibration more quickly, but they’re still better than not measuring at all.

Meters that measure pH or EC directly in the substrate can be helpful, but if they are not from a well-known, scientifically validated brand, their readings are often unreliable. If you choose to use them, treat the numbers as a rough guide and avoid making major decisions based solely on those measurements.

Calibration and solutions

All pH meters must be calibrated regularly with calibration solutions. EC meters can also be checked and calibrated with a reference solution. It is important to keep the electrode clean and store it in a storage solution to maintain its lifespan and accuracy.

Water temperature plays an important role in accurate pH and EC/TDS measurements. Both values shift with temperature, and if the water is significantly warmer or colder than room temperature, your readings may be off.

Many meters include automatic temperature compensation, but this feature does not correct extreme differences. For the most consistent results, always let your water reach a stable, room-temperature range before measuring.

What is a pH meter

A pH meter is a handheld device that measures how acidic or alkaline your water or nutrient solution is. Because nutrient availability changes with pH, using a pH meter helps you keep your irrigation water, nutrient solution and runoff within the optimal range for healthy nutrient uptake.

How to calibrate and use a pH meter

Calibration steps:

1. Clean the probe: Rinse the pH meter probe with distilled water to remove any residue from previous readings. Gently blot it dry with a lint-free cloth or paper towel. Avoid rubbing the probe, as this can damage it.
2. Prepare calibration solutions: You’ll typically need at least two calibration solutions, usually pH 4.0 and pH 7.0. Calibrate with pH 7.0 solution:

• Turn on the meter and dip the probe in the pH 7.0 buffer solution.
• Wait for the reading to stabilize, then press the “calibrate” button (or adjust using the settings, depending on your meter) to set it to 7.0.

3. Rinse the probe: Rinse with distilled water and blot dry before moving to the next buffer solution.
4. Calibrate with pH 4.0 solution:

• Dip the probe into the pH 4.0 buffer solution.
• Once the reading stabilizes, press the “calibrate” button to set it to 4.0.

5. Check the calibration: Rinse and check in both pH 7.0 and pH 4.0 solutions again to ensure accuracy. If the readings are off, repeat the calibration steps.
6. Storage: After calibration, store the probe in the manufacturer-provided storage solution. Never let the pH probe dry out if it’s intended for storage in a solution

Using your pH meter:

1. Rinse the probe with distilled water before taking a new measurement.
2. Dip the probe in the solution you’re testing and wait for the reading to stabilize.
3. Rinse the probe with distilled water after every use to prevent residue buildup and contamination.

What is an EC/TDS meter?

An EC/TDS meter measures the electrical conductivity or total dissolved solids in your water or nutrient solution. This tells you how concentrated your nutrients are, helping you avoid both underfeeding and overfeeding while keeping your plants in a stable and balanced environment

How to calibrate and use an EC meter

Calibration Steps:

1. Rinse the probe: Before calibration, rinse the EC meter probe with distilled water and gently blot it dry.
2. Prepare the calibration solution: Use a standard EC calibration solution (commonly 1.41 mS/cm, but your meter might require a different standard).
3. Dip the probe in the calibration solution: Turn on the meter and submerge the probe in the calibration solution. Wait until the reading stabilizes.
4. Calibrate: Adjust the meter to match the EC value of the calibration solution (follow the specific instructions provided with your meter, which may involve pressing a “calibrate” button or manually adjusting).
5. Rinse the probe: Rinse with distilled water and blot dry before taking any measurements.

Using your EC meter:

1. Rinse before use: As with the pH meter, rinse the EC probe with distilled water before taking a new measurement.
2. Measure: Submerge the probe into the solution to be tested and wait for the reading to stabilize. Note the EC value.
3. Rinse after use: Rinse the probe with distilled water after each use to maintain accuracy.
4. Turn on the meter and dip the probe in the pH 7.0 buffer solution.
5. Wait for the reading to stabilize, then press the “calibrate” button (or adjust using the settings, depending on your meter) to set it to 7.0.

General maintenance tips for both meters

• Calibration frequency: Calibrate your meters regularly, especially before critical measurements. For frequent use, calibrate at least once a week.
• Storage: Store the probes according to the manufacturer’s instructions. pH probes should be kept in a storage solution, while EC probes should be kept dry and clean.
• Temperature compensation: Many modern pH and EC meters come with automatic temperature compensation (ATC), but always check your device. For EC meters, make sure the solution and environment are at a stable temperature to ensure accurate readings.
• Cleaning solutions: Regular maintenance is essential for keeping any pH or EC/TDS electrode accurate and responsive. Cleaning the probe removes dirt and sediment that builds up on the glass or carbon surfaces of the sensor, which helps maintain both performance and precision. Keep in mind that electrode cleaning solution is not a replacement for proper rinsing or for the required storage solutions that protect the probe between uses.

Understanding EC readings

Even high-quality meters have a ±5% accuracy margin, so treat EC as a guide rather than an exact value. EC/TDS measures the total amount of dissolved fertilizer salts, which changes as plants absorb water and nutrients.

When water evaporates or plants transpire, EC rises; when plants consume nutrients faster than water, EC drops

In hydroponic systems, check EC every 1–2 days, refill with clean water to lower EC, and add fertilizer only if it falls below your target.

In growing mixes like coco or peat, check weekly using the PourThru method.

Testing methods

The way you measure pH and EC greatly affects your results, just like weighing something with your hand isn’t the same as using a scale.

For growing mediums (anything that isn’t a hydroponic system),I recommend using the PourThru test, which provides consistent and comparable readings. Check out the next article, where I explain step by step how to do it and share the target pH and EC values for each stage of cannabis growth.

Track your measurements for better results

Log your pH and EC readings in the Grow with Jane app to track your progress over time. The more consistent your measuring method and frequency are, the more reliable your data will be, helping you spot trends, prevent issues early, and fine-tune your plant’s nutrition with confidence.

Proper pH and EC levels support strong root development, balanced nutrient uptake, and steady growth, which reduces the risk of deficiencies and stress. By keeping these basics under control, you lay the foundation for healthy, vigorous plants that perform well throughout each stage of the grow cycle.

If you start noticing yellowing, spots, or other marks on the leaves, I recommend checking the nutrient deficiencies section to help identify the issue. Many leaf symptoms are directly related to pH imbalances or EC spikes, which affect how well the plant can absorb nutrients. Catching these early and correcting the underlying cause will help your plants recover more quickly and continue growing strong.

Happy growing!