Nutrients Concentration by Electrical Conductivity (EC)

Dissolved Nutrients are in an ionic form into water and will be available to be absorbed by plants. The more ions present, the better the water conducts electricity.

Measuring the electrical conductivity of the water is the way of measuring the strength of your nutrient solution.

Whatever it doesn’t give information about individual nutrients, it’s a highly useful guide to its overall strength. By experience, the user will know the EC of the formula (NPK, Acid) he wants to inject. Lowing down, the EC will inform that nutrient are missing.

Therefore, different plants have different ranges of EC value for optimal growth.
In general, if your EC is very low, your plant probably doesn’t have enough food. If your EC is very high, you may run the risk of burning the roots or toxic buildups.
The scientific scale the most used is milli-siemens per centimeter (mS/cm2).

EC value will be variable for the same plant at different ages.

Measuring Electrical Conductivity (EC)

Salinity is determined by the concentration of total dissolved salts. In water and/or suspensions, salt ions are completely free and mobile and can be measured by means of electrical conductivity (EC): the higher the electrical conductivity, the higher the salt concentration.

How to measure EC:

The simplest way is to use a digital EC meter.
Various types of measuring EC in solution and other growing media. 

Conductivity measurement for salinity determination of liquids and solutions. The measuring range up to 200 mS even allows precise measurements of fertilizer stock solutions.

Is EC the same as soil salinity?

Basically it is important to know that there is no EC measurement directly in the soil possible because not all salt ions are dissolved and thus cannot be taken up by the roots. Therefore, we do not call salinity measurement directly in a substrate or soil “EC measurement”, because it can take place only in a solution (RO Water), even though the expression “EC measurement in soil” is used colloquially.

Necessity of good pH to make nutrient available to the plants.

The pH is to determine whether the nutrients you add are available for the plant to absorb it. Control the pH and you’ll help ensure that the plant gets all the nutrients it needs. Different plants have their own preferences for pH values.

Trying to grow without managing pH can cause nutrient lockout. The nutrients become insoluble and unavailable to the plant.

You may be faced with the following challenges:
• Slow and stunted growth.
• Leaf, flower, and fruit drop.
• Leaf discoloration.
• Root burn.
• Chemical imbalances/overuse of nutrient solutions.
• Pests and diseases.
• Crop failure.

The pH is to determine whether the nutrients you add are available for the plant to absorb it. Control the pH and you’ll help ensure that the plant gets all the nutrients it needs. Different plants have their own preferences for pH values.

Trying to grow without managing pH can cause nutrient lockout. The nutrients become insoluble and unavailable to the plant.

The absorption of nutrients by the plants depends to a large extent on the acidity of the soil or substrate:

  • low рН blocks the macro elements absorbability
  • high рН (alkaline reaction) blocks microelements absorbability 

For this reason, quick and accurate pH measurement is an essential condition in the optimization of plant nutrition in professional horticulture.

The pH has many effects, mainly on nutrients solubility and their ionic form. At different levels of pH some nutrients may be deficient while others might reach high concentrations to cause toxicity. At high basic pH, most micro-elements will suffer from availability problems. Most plants would prefer to grow within the pH range of 6 to 6.5 that will assure high availability of most demanded nutrients.

Measuring pH in different growing environments.

What can change the pH of soil:

  • The plant itself: Plants can change the pH of soil or media. The plant taking up nutrients or releasing ions into the root zone can affect the pH in soil.

By how much depends on their stage of growth. Recording pH levels through the growing cycles are helpful. It’ll give you a useful history, so you know whether the values you see are expected.

  • Applications of and types of fertilizers: These can alter the pH significantly. Some fertilizers can make your pH level head in a direction you don’t want.

Nutrient stock solution is usually slightly acidic and may lower the pH.

  • Applications of sprays: These can soak into the soil or growing media and change your pH.
  • The carbonate in water works to neutralize the slightly acidic water in your reservoir. As the water in your tank is topped off, the pH value will rise.
  • Soil/media temperature: Soils with high temperatures can have a high concentration of carbon dioxide (CO2). This leads to the production of more carbonic acid, which lowers pH.
  • Adding Acidic solution or Buffer can control the pH.

BEST pH to make nutrient available

Different plant species had different optimal pH values where the best quality plants were produced.

A wide range of set pH values can be used, from 4.5 to 7.5

For example, tomatoes grew best at pH 6 and petunias had a 50% growth increase at pH 4.5 than when they were grown at any other pH value. If the pH value of the root zone is the optimal one for that species, the plant will grow better than if the pH was not controlled.

In fact, there was a 44% loss in tomato yield when there was no control of the pH.
These findings clearly show the importance of taking regular pH measurements and controlling this in the growth environment to increase and optimize production levels.

Table of standard pH values by “StepSysytems” 

Agricultural Crop: vegetables pH value  Agricultural Crop:     plants pH value
 Asparagus 6.2 – 6.6  Adiantum 4.5 – 6.0
 Beans 5.8 – 6.4  Anthurium andreanum 4.5 – 5.5
 Beetroot 6.2 – 6.6  Begonia elatior 5.0 – 6.5
 Broccoli 6.2 – 6.6  Bromelien 4.0 – 5.5
 Bush beans 6.0 – 7.5  Buxus sempervierens 6.0 – 8.0
 Cabbage 6.2 – 6.6  Calluna vulgaris 4.0 – 5.0
 Carrot 5.8 – 6.4  Camelia japonica 4. 0 – 5.5
 Chicory 5.5 – 6.4  Chriysanthemum indica 5.5 – 7.0
 Cucumber 5.8 – 6.4  Erica gracilis 3.5 – 4.5
 lettuce 5. 5 – 7.5  Gerbera jamesonii 5.0 – 6.5
 Onion 6.0 – 7.0  Hydrangea blue 3.5 – 4.5
 Paprika 6.0 – 7.5  Impatiens 5.5 – 6.5
 Pieplant 5.5 – 6.4  Lilium hybriden 5.5 – 7.0
 Potato 5.5 – 6.4  Orchideen epiphyt. 4.5 – 5.5
 Radish 5.5 – 7.0  Petunia hybrida 5.5 – 6.5
 Spinach 5.5 – 7.5  Philodendron 5.0 – 6.0
 Strawberry 5.5 – 6.4  Primula vulg./acaulis 5.5 – 6.5
 Sugar pea 5.8 – 6.4  Rhododendron japanische 4.0 – 5.5
 Sweet corn 5.8 – 6.4  Rose multiflora 5.5 – 7.0
 Tomato 5.8 – 6.4  Saintpaulia ionantha 5.0 – 6.5
 Watermelone 5.5 – 6.4  Thuja occid. columna 6.0 – 8.0

All nutrients have their best pH scale to be absorbed by the plants. To have all of them taken in an optimum range as following:


Special Dosing Pump made in PVDF to resist against high concentration of Acid with very low pH less than 1 in stock solution.

Where to measure the pH and the EC ?

• In the reservoir: It is where is the solution that will be used to feed the plants. It must have sufficient nutrient concentration to do this.
• Inline, in the water supply: It is the easiest way and can be automatic.

Note: Important to have clean water supply because there is a risk of contaminate ions giving an EC value. This may affect your actual EC value and may prevent optimal nutrient availability for the plant. A good Filtration (ie. at 1mcr. or even 0.2 mcr.) is a necessity to maximize the accuracy of the EC.

Multi-Dosing Solutions with EC and pH control.
Hydroponics, Vertical Farming, Aquaponics, Aeroponics, Drip Irrigation …

pH and Electrical Conductivity (EC) Measurement

Hydroponic Buffer Tank Control before refilling the water bath with right EC and pH: