GrowShop editorial guide
What is the difference between pH and EC meters?
pH describes acidity or alkalinity; EC provides an indirect indication of conductivity and total dissolved ions. One does not replace the other.
What do pH and EC measure?
pH indicates acidity or alkalinity, which affects nutrient availability. EC measures the conductivity of ions in the solution; it does not identify individual nutrients.
Suitable values vary by plant, growth stage, source water, and system. There is no universal target value.
Meter selection checklist
- Replaceable or serviceable probe
- Suitable calibration solutions
- Clear explanation of temperature compensation
- Measurement range and resolution
- Storage and cleaning instructions
- Warranty and spare parts
Build a reliable measurement habit
Calibrate as directed, clean and store the probe correctly, and record readings with date and time. Measuring source water separately from the prepared nutrient solution makes changes easier to interpret.
pH, EC and TDS at a glance
| Reading | Meaning | Limit |
|---|---|---|
| pH | Acidity or basicity | Not the nutrient amount |
| EC | Electrical conductivity | Not the concentration of each nutrient |
| TDS / ppm | Estimate converted from EC | Requires the meter's conversion scale |
References: Oklahoma State University Extension; Bluelab
Units and conversion scales
1 mS/cm equals 1,000 µS/cm. For 1.0 mS/cm, a ppm-500 meter displays 500 ppm and a ppm-700 meter displays 700 ppm. The same solution can therefore have different ppm readings. Record the scale with the result.
References: Bluelab
Resolution, accuracy and probe maintenance
Resolution is the smallest displayed increment; it does not establish measurement accuracy. Compare both specifications, the replaceable probe and access to consumables.
Follow the model's calibration and storage instructions. Some conductivity meters need verification rather than user calibration. For OnePen, Bluelab specifies KCl storage and a hydrated, clean pH probe; do not generalise one model's procedure to every probe.
References: Bluelab; Bluelab Support
Before interpreting a measurement
- Record source-water and prepared-solution readings separately.
- Record the date, temperature, unit and calibration or verification status.
- A similar EC can hide different nutrient balances; diagnosis may require water analysis.
- Use crop, growth stage, water and system information rather than one universal pH/EC target.
References: Oklahoma State University Extension
Sources
Technical explanations on this page are independent summaries based on the institutional sources below.
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