What Is EC In Hydroponics?


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In hydroponics, electrical conductivity (EC) is the measurement of conductance/conductivity within your hydroponic nutrient solution; EC tells you the number of available nutrients in your hydroponic system. Electrical conductivity is measured using an EC meter

Hydroponics is a rapidly growing field that allows individuals to grow plants without soil, using a nutrient-rich solution instead. However, to ensure optimal plant growth and development, it’s important to understand the concept of electrical conductivity (EC) in hydroponics. EC is a measure of how well an electrical current can travel through a solution, and it plays a crucial role in determining the nutrient levels in a hydroponic system. 

Essentially, the EC of your hydroponic solution will determine how much food your plants receive, and how well they can absorb it. So, if you’re looking to maximize your hydroponic plant growth and yield, it’s essential to understand the basics of electrical conductivity and how it impacts your nutrient solution. In this article, we’ll explore everything you need to know about EC in hydroponics, including how to measure it and how to maintain optimal levels for your plants.

EC Units

Distilled (pure) water has a conductance level of 0 as it has no minerals. As soon as minerals (salts/ions) are dissolved into the water, the water can conduct electricity and provide an EC value. The higher the salt concentration in the water, the higher the EC. By measuring the EC in your hydroponic system, the EC value will tell you how many nutrients are in the water.

Electrical conductivity uses several units, however, the most common EC units are millisiemens per centimeter (mS/cm) or parts per million (ppm), which can then be converted into milligrams per liter (mg/L). 

EC units can be converted using a fixed calculation:

1 ppm = 0.998859 mg/L

Should You Use PPM Or EC In Hydroponics?

In hydroponics, it is common to express the concentration of nutrients in the nutrient solution in terms of parts per million (ppm) or electrical conductivity (EC). PPM is a measure of the concentration of dissolved salts in the nutrient solution, directly related to total dissolved solids, while EC is a measure of the ability of the solution to conduct an electrical current.

Both PPM and EC can be used to monitor the nutrient concentration in the nutrient solution. However, EC is the preferred method for measuring the nutrient concentration in hydroponics because it is a more accurate and reliable measure of the concentration of dissolved salts in the solution.

What Is The Difference Between EC & TDS?

Total dissolved solids (TDS) measure both the EC-generating particles AND the particles that are unable to conduct electricity in the water. Whereas, EC looks at the behavior of the electricity in the water, and therefore the ions that conduct electricity only. 

Why Is Electrical Conductivity Important In Hydroponics?

By measuring EC in hydroponics, you will get a better understanding of your system’s nutrient feed. Gradually, your system’s EC value will either remain stable or it will fluctuate, which is why it is essential to measure EC frequently. 

If the EC remains stable, it shows that your plants are optimizing the same amount of water as it is nutrients. When this happens, ensure the nutrient tank is refilled with the same solution strength, and check the EC regularly, so it doesn’t drop or fall. 

If the EC level drops, it is an indication that your plant is uptaking more nutrients than water. So, if the EC has fallen dramatically, top up with a stronger hydroponic nutrient solution. If you decide on using a stronger solution, monitor the EC level closely to check how your plants are responding. 

If the EC level has risen, this means that your plants are uptaking more water than nutrients. It can also be an effect of temperature increases in the surrounding environment; when temperature increases, plants uptake more water. This can be an issue as your plants are not taking up what they need to grow. To solve the problem, add more water to dilute the hydroponic solution. Signs of overfeeding plants include leaf burn and impaired growth.

By measuring EC in your hydroponic system, you will know when you need to top up your nutrient solution. It is important to note that measuring EC in hydroponics only tells you how many nutrients are available, not the level of individual elements. 

Does EC Determine Nutritional Value?

Electrical conductivity indicates the presence of mineral salts in water, however, it does not necessarily indicate that the nutritional salts in the water are beneficial to your plant(s). For example, tap water has an EC value due to the presence of sodium and chloride ions, however, it has no nutritional value for plant growth. 

When nutritional salts are added to water (i.e. fertilizer), the nutritional value is referred to as EC+ and should be added to the residual EC of the water. This is how hydroponic farmers measure the total EC in feeding tanks. 

How To Measure EC In Hydroponics?

To measure the electrical conductivity in hydroponics, you will need an electrical conductivity meter. They are simple to use and come in two forms: handheld and inline. Handheld meters are portable and allow you to measure electrical conductivity at any point in the system. Inline meters are installed in the nutrient solution flow path and continuously monitor the electrical conductivity.

At Atlas Scientific, we offer a full Hydroponics Kit, so you do not need to worry about measuring other parameters in your hydroponic garden. With our Wi-Fi Hydroponics Kit, you can measure pH, conductivity, and temperature all at once. With the built-in Wi-Fi settings, it allows for remote readings on your phone, tablet, or PC, so you can have a close eye on your plant’s health at all times.

To measure the electrical conductivity, you will need to take a sample of your nutrient solution using a clean container. Rinse the container with distilled water before taking the sample to avoid contamination. Once you have the sample, make sure the meter is calibrated according to the manufacturer’s instructions. Then, dip the meter’s probe into the solution and wait for the reading to stabilize. The conductivity meter will display a number that represents the electrical conductivity of the solution in units of millisiemens per centimeter (mS/cm). Once you have finished using the EC probe, clean it with a proper EC probe cleaner and store it correctly. 

The ideal electrical conductivity level for hydroponic plants varies depending on the stage of growth and type of plant. Therefore, it is important to research the specific needs of the plants you are growing to determine the ideal electrical conductivity level.

Note: Don’t forget to calibrate your meter regularly and use clean containers to avoid contamination.

How Often To Measure EC In Hydroponics?

You should measure EC every day in hydroponics. This way, you can top up nutrients before the levels become too high or too low. We recommend performing a complete nutrient refresh every week by draining the nutrient tank and making a new solution. 

Benefits Of Measuring EC In Hydroponics

The biggest benefit to measuring EC in hydroponics is the control you have over your system. Measuring EC allows you to adjust the nutrient level as needed. 

Another benefit is to avoid over or under-watering your plants. Under-watering plants turn brown and dry out, usually resulting in plant death. However, if your plant has enough water to survive it will still grow, but much slower than expected.

On the other hand, if you are overwatering your plants they will have droopy leaves, due to excess water in the leaves and yellow leaves from nutrient imbalance. Overwatering also causes slow growth from the lack of oxygen exposure. 

Frequently monitoring EC in hydroponics is the key to successfully growing healthy plants and ensuring they have all nutrients they need.

Ideal EC For Plants

The ideal electrical conductivity for plants can vary depending on the species and growing conditions, but generally falls within a specific range.

The electrical conductivity of the soil is directly related to the nutrient availability and uptake by the plants. Too high or too low EC can cause nutrient imbalances, leading to stunted growth, yellowing of leaves, and other problems. The optimal EC value for plant growth is typically between 1-2.5. This range is considered optimum for the majority of plants and ensures that the nutrients are available in the right amounts and ratios for healthy growth. EC values in hydroponics should not exceed 2.5 unless the plant/crop requires a high EC level. 

Saying that, typically during the vegetative stage, the EC should be maintained between 1.2-1.6. Once flowering has happened, the EC should be between 1.6-2.4.

It’s important to note that the ideal electrical conductivity for plants can vary depending on the crop and growing conditions. For example, hydroponic systems require a higher EC range than soil-based systems due to the absence of natural nutrients in the water. In contrast, certain crops such as blueberries and strawberries require a lower EC range due to their sensitivity to high salt concentrations.

Hydroponic Plants/Cops: pH & EC Values

Below is a list of common hydroponic plants and crops and their ideal EC and pH value. 

Plant/CropEC LevelpH Level

What Is The Relationship Between pH And Electrical Conductivity?

The relationship between pH and EC is complex and can be affected by several factors, so complex in fact that it could take up a whole textbook chapter! The good news for you, is we have a simplified explanation. 

As the pH of a solution increases (becomes alkaline), the concentration of H+ decreases, which leads to a decrease in electrical conductivity. Conversely, as the pH of a solution decreases (becomes acidic), the concentration of H+ increases, which leads to an increase in electrical conductivity.

However, the relationship between pH and EC is not always straightforward. Other factors, such as the presence of dissolved salts or other ions in the solution, can also affect the electrical conductivity of the solution. For example, a solution with a low pH but high salt content may have a higher electrical conductivity than a solution with a higher pH but lower salt content. This is because the dissolved salts in the solution can contribute to the electrical conductivity independently of the pH.

How To Reduce EC In Hydroponics?

One common issue that hydroponic growers face is high EC levels in their nutrient solution. High EC in water comes from an increase in salinity, groundwater inflows, and an increase in temperature. 

High EC levels can lead to the following symptoms:

  • Discolored leaves
  • Thicker roots than usual
  • Tissue necrosis
  • Wilted stems and leaves

Luckily, there are ways to combat this issue and reduce electrical conductivity in hydroponics.

One way to reduce electrical conductivity in hydroponics is to use reverse osmosis (RO) water in your system. RO water is purified through a process that removes most impurities, including minerals that contribute to high EC levels. By using RO water as the base for your nutrient solution, you can start with a lower EC level and add nutrients as needed to reach your desired EC level.

Another way to reduce electrical conductivity in hydroponics is to adjust your nutrient solution. EC levels are directly related to the concentration of dissolved solids in the water, including nutrients. By adjusting the amount and type of nutrients in your solution, you can lower the EC level. Be sure to monitor pH levels as well, as nutrient availability can be affected by pH levels.

You can also reduce electrical conductivity in hydroponics by flushing your system periodically. Flushing involves running plain water (pH-balanced water) through your system to remove any excess salts or nutrients that may have built up over time. This can help to reset the EC level of your nutrient solution and prevent nutrient lockout.

How To Increase EC In Hydroponics?

If your plants are suffering from low EC levels, you can look out for the following signs and symptoms:

  • Discolored leaves (typically they turn brown or yellow)
  • A noted difference in crop yield
  • Stunted roots
  • Stunted growth
  • Pits in the leaves
  • Brown spots on the leaves
  • Leaf necrosis
  • Stunted or misshapen leaves

Increasing the EC is much more straightforward than reducing the EC. The easiest way is to add more nutrient solution or a fertilizer. When doing so, remember to measure the EC frequently.

Is EC Affected By Water Quality In Hydroponics?

Absolutely! The quality of water directly impacts electrical conductivity. The more salts in water will increase the EC value. So, the type of water that you use in your hydroponic system will have a direct effect on the EC value. 

If you are using hard water in hydroponics, the nutrient content will be greater than using soft water. The most common nutrients in hard water are calcium and magnesium ions, both of which are essential plant nutrients. Hard water also contains dissolved metals such as aluminum, iron, zinc, manganese, and barium. 

If you are unsure whether your water source is hard or soft you can send a water sample to an approved laboratory to check the mineral content. 


Measuring electrical conductivity in hydroponics is an essential part of maintaining a healthy and productive garden.  It’s important to regularly monitor your nutrient solution’s EC levels and adjust accordingly. Aim for an EC level that is appropriate for the growth stage of your plants and the specific crop you are growing. By keeping a close eye on your EC levels and making adjustments as needed, you can prevent plant stress and nutrient deficiencies, and promote healthy growth in your hydroponic garden.

If you have any questions regarding the EC in your hydroponic system, or what EC probes we have in store, do not hesitate to contact the world-class team at Atlas Scientific.

Conductivity Probes & Circuits

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