8. EC and pH: what they are and why they matter in hydroponics

In hydroponics you can have the best LED, the best greenhouse, the best genetics... but if EC and pH are not under control, the plant will not grow as it should.
These are two parameters that are simple to measure, but critical to understand. In this article I explain what they are, how they work, and why they determine the success of any hydroponic grow.

What is pH and why it is critical

pH measures how acidic or basic a solution is.
Different nutrients are absorbed by the plant only in a certain pH range: if you go outside this range, the elements get stuck and the plant goes deficient--even if the nutrients are there.

The ideal range in hydroponics

• 5.5 to 6.5 for most leafy vegetables.

• Lower values favor uptake of Fe, Mn, B, Zn,

• Higher values favor Ca, Mg, K

pH is not "just" a number: it is the key that unlocks nutrients.

What is EC and what it really measures

EC (Electrical Conductivity) indicates how much electrical current flows through water: the more nutrients there are, the higher the conductivity.

Basically: EC = concentration of the nutrient solution.

An EC too low → deficiencies and slow growth
An EC too high → osmotic stress and risk of root burns

Guideline values in hydroponics

• Germination: 0.4 - 0.8 mS/cm

• Vegetative growth: 1.0 - 1.5 mS/cm

• Final leaf stage: 1.2 - 1.8 mS/cm

Each species has its own sweet spot.

Why do EC and pH change during the day?

The plant absorbs water and nutrients in different proportions:

• If it absorbs more water → EC rises

• If it absorbs more nutrients → EC goes down

• Photosynthesis changes the root environment → pH can fluctuate

This is why it is not enough to set them once: constant control (or automation) is needed.

EC and pH in Tomato+ greenhouses: automatic and optimized control

In Tomato+'s Horto Professional greenhouses, EC and pH are not "measured": they are actively managed.

Thanks to:

• integrated professional sensors

• AI models that observe the rate of growth

• continuous telemetry and automatic feedback loops

the software identifies:

• whether the plant is entering stress,

• whether uptake is imbalanced,

• whether concentration or acidity needs to be increased or reduced,

• how to optimize the EC curve based on actual growth rate.

In advanced systems like Horto Professional, EC and pH become part of a dynamic Growth Plan, not static parameters.

This allows:

• higher yields,

• more consistent leaves,

• lower risk of root disease,

• optimization of water and nutrient consumption.

In short: intelligent parameter management eliminates the margin for human error and makes cultivation much more predictable and efficient.

How to keep EC and pH under control (if you don't have a Tomato+ greenhouse)

If you grow manually:

1. Measure every day, always at the same time.

2. Use low-mineral water.

3. Maintain the correct range for the species.

4. Change the nutrient solution regularly.

5. Remember: stability is more important than perfect numbers.

Conclusion

EC and pH are at the heart of hydroponics: controlling them means controlling growth.
With automated and AI systems like Tomato+'s, management goes from "complicated" to "invisible," leaving the plant with the best possible environment to express its potential.

Thank you for reading this article. Keep following us to discover new content on hydroponics, vertical farming, and smart agriculture.
Tomato+ Team