Reference guide for EC, pH, ppm, temperature, and other key measurements used in Hydrogene Pro.
Measurements Reference
This page explains the measurement variables tracked in Hydrogene Pro, how they are used, and what values to target for common growing scenarios.
Electrical Conductivity (EC)
What it is: EC measures the total concentration of dissolved ions in a nutrient solution. It is used as a reliable indicator of overall nutrient strength.
Unit: mS/cm (millisiemens per centimeter)
How it works: As you dissolve more fertilizer salts in water, EC increases. A higher EC means a more concentrated solution; a lower EC means a weaker solution.
General target ranges:
| Growth Stage | EC Range (mS/cm) |
|---|---|
| Seedlings / Clones | 0.5 – 1.2 |
| Early Vegetative | 1.2 – 2.0 |
| Late Vegetative | 1.8 – 2.5 |
| Early Bloom | 2.0 – 2.8 |
| Late Bloom | 2.4 – 3.2 |
| Flush | 0.0 – 0.5 |
These ranges are general guidelines. Your specific crop, strain, and growing system may require adjustments. Always use your feed chart’s defined target ranges as the primary reference.
In Hydrogene Pro: EC targets are defined per week in the Feed Chart and displayed in the Dashboard’s EC progression chart. Measured EC values are logged in the Measures tab.
pH
What it is: pH measures the acidity or alkalinity of a solution on a scale from 0 to 14. It directly affects the availability of nutrients to plant roots — even if the right nutrients are present, an incorrect pH can prevent uptake.
Unit: pH units (dimensionless scale)
General target ranges:
| Growing Medium | Target pH |
|---|---|
| Hydroponics (DWC, NFT, rockwool) | 5.5 – 6.2 |
| Coco coir | 5.8 – 6.3 |
| Soil | 6.0 – 7.0 |
| Perlite | 5.8 – 6.5 |
Nutrient availability by pH:
- Below 5.5: Risk of iron, manganese, and zinc toxicity; reduced calcium and magnesium uptake.
- 5.8 – 6.5: Optimal range for most hydroponic crops — good availability of all macro and micronutrients.
- Above 7.0: Iron, manganese, zinc, boron, and copper become increasingly unavailable.
In Hydrogene Pro: pH targets are set per week in the Feed Chart and visualized in the Dashboard’s pH progression chart. pH readings are logged in the Measures tab.
Parts Per Million (ppm)
What it is: ppm measures the concentration of a specific nutrient in a solution. It provides more precise, element-level information than EC alone.
Unit: mg/L (equivalent to ppm)
How it relates to EC: EC gives a combined total of all dissolved ions; ppm tells you how much of a specific element (e.g., nitrogen, calcium) is present. Both are useful — EC for quick field checks, ppm for diagnostic precision.
Conversion note: Different instruments use different conversion factors (TDS meters). Common factors are 0.5 (US) and 0.7 (European). Be consistent and document which factor your meter uses.
In Hydrogene Pro: The Dashboard’s Nutrient Levels chart shows expected ppm for each nutrient by cultivation week. Measured ppm values can be logged in the Measures tab and compared to expected targets.
Temperature
What it is: Ambient or nutrient solution temperature. Both affect plant metabolism, oxygen levels in the root zone, and the activity of beneficial microbes.
Unit: °C or °F (Hydrogene Pro uses the unit configured in your account settings)
General target ranges:
| Parameter | Optimal Range |
|---|---|
| Air temperature (lights on) | 22°C – 28°C (72°F – 82°F) |
| Air temperature (lights off) | 18°C – 22°C (64°F – 72°F) |
| Nutrient solution temperature | 18°C – 22°C (64°F – 72°F) |
Why it matters: High solution temperatures reduce dissolved oxygen and promote root pathogens. Low temperatures slow nutrient uptake and plant metabolism.
In Hydrogene Pro: Temperature is logged in the Measures tab and tracked in the Dashboard’s EC/pH/Temperature Progression chart.
Humidity (Relative Humidity, RH)
What it is: The percentage of water vapor in the air relative to the maximum it can hold at that temperature.
Unit: % RH
General target ranges:
| Growth Stage | RH Range |
|---|---|
| Clones / Seedlings | 70% – 80% |
| Vegetative | 50% – 70% |
| Early Bloom | 40% – 60% |
| Late Bloom | 30% – 45% |
Why it matters: High humidity during flowering increases the risk of mold and botrytis. Low humidity increases plant stress and water loss.
In Hydrogene Pro: Humidity is logged in the Measures tab and visible in the Dashboard.
Plant Number Notation
When logging measurements or events for specific plants, Hydrogene Pro uses the following notation:
| Notation | Meaning |
|---|---|
1-4 | Plants 1, 2, 3, and 4 (sequential range, use a hyphen) |
2, 9 | Plants 2 and 9 only (non-sequential, use commas) |
1-3, 7, 10 | Plants 1, 2, 3, 7, and 10 |
Using plant numbers consistently makes it much easier to trace issues back to specific locations in your grow space.
Related
- Cultivation Cycle — Measures Tab — How to log measurements.
- Cultivation Cycle — Dashboard Tab — How to visualize measurement data.
- Glossary — Definitions of nutrient and agronomy terms.