In the realm of hydroponic gardening, where plants thrive in nutrient-rich water solutions rather than traditional soil, monitoring the quality and composition of the nutrient solution is crucial for optimal plant growth. Two key parameters that hydroponic growers often rely on are Total Dissolved Solids (TDS) and Conductivity.
According to TDS and EC, you can infer the overall concentration and ionic content of a hydroponic nutrient solution. Specifically, TDS refers to the total amount of dissolved substances in the water, including minerals, salts, and other nutrients, while Conductivity measures the ability of the solution to conduct an electric current, which is directly related to the presence of ions in the solution.
In this post, we’ll find out the differences between TDS and EC, exploring how they are measured and how each parameter impacts nutrient management and plant growth.
What Is TDS?
TDS, or Total Dissolved Solids, is the combined amount of all inorganic and organic substances dissolved in a liquid. Typically, it's measured in parts per million (ppm) or milligrams per liter (mg/L). In hydroponics, TDS is used to gauge the concentration of nutrients and minerals in the nutrient solution.
A higher TDS value indicates a greater amount of dissolved solids, which can be beneficial for providing plants with essential nutrients. However, it must be carefully managed to avoid over-fertilization or nutrient imbalances. TDS measurements help growers maintain optimal nutrient levels, ensuring healthy plant growth and development.
What Is EC?
EC, or Electrical Conductivity, measures a solution's ability to conduct an electric current. Typically, it's expressed in units of microsiemens per centimeter (µS/cm) or millisiemens per centimeter (mS/cm). In hydroponic gardening, EC is used to assess the concentration of dissolved ions in the nutrient solution.
Since ions like calcium, magnesium, and potassium are essential for plant growth, a higher EC value generally indicates a more nutrient-rich solution. However, EC does not specify the types of ions present, only their total ionic concentration. Regular EC monitoring helps growers adjust nutrient levels to prevent deficiencies or toxicities, ensuring optimal plant growth and health.
How to Test TDS and EC?
The Spider Farmer 5-in-1 pH Hydroponic Meter Kit is a multifunctional TDS and EC meter. It combines a TDS and an EC meter, pH, temperature, and salinity measurements, all in one device. More importantly, you can read TDS and EC values on the same screen, so that you don’t need to take time to convert TDS to conductivity. By providing accurate readings of essential parameters, it helps you to keep optimal nutrient uptake.
- 5-in-1 Accurate Measurements: Measures pH, EC, TDS, temperature, and salinity.
- TDS & pH on One Screen: Demonstrate TDS and pH readings on the same screen, helping you to get a faster and more precise nutrient management.
- High-Sensitivity Sensor: Provides stable readings with ±0.05 pH accuracy, preventing nutrient issues and fertilizer waste.
- Long-lasting Battery: Built-in 600mAh lithium battery supports 300 cycles, with up to 6 months standby for every charge.
How to Convert TDS to EC?
You can convert TDS to EC. The relation is expressed by a formula: TDS (ppm)=K×EC(μS/cm)
TDS Conversion to Conductivity
- TDS (ppm) is the total dissolved solids in parts per million.
- EC (µS/cm) is the electrical conductivity in microsiemens per centimeter.
- K is the conversion factor, which typically ranges from 0.5 to 0.8 and is often taken as 0.64
For example, if you have an EC reading of 1000 µS/cm and a conversion factor (K) of 0.64, the TDS can be calculated as: TDS (ppm)=0.64×1000=640 ppm
The conversion factor (K) or the ratio of conductivity to TDS varies depending on the type of water and the ions present in the solution. The common ratio of conductivity to TDS is:
- Pure water: 0.55 - 0.60
- Tap water: 0.50 - 0.70
- Groundwater: 0.65 - 0.70
- Seawater: 0.50
Total Dissolved Solids Vs Conductivity
In this part, we’ll compare TDS and EC from the perspectives of definition, measurement, conversion, advantages, disadvantages, and applications.
|
Aspects |
TDS (Total Dissolved Solids) |
EC (Electrical Conductivity) |
|---|---|---|
|
Definition |
Measures the total amount of dissolved substances (minerals, salts, and other nutrients) in the solution, reported in parts per million (ppm). |
Measures the ability of the solution to conduct electricity, indicating the presence of ions, reported in microsiemens per centimeter (µS/cm) or millisiemens per centimeter (mS/cm). |
|
Measurement |
Uses a TDS meter that estimates the concentration of dissolved solids based on the electrical conductivity of the solution. |
Uses an EC meter that directly measures the electrical conductivity of the solution. |
|
Conversion |
TDS is calculated from EC using a conversion factor (commonly 0.5 to 0.8). For example, TDS (ppm) = EC (µS/cm) × Conversion Factor. |
EC can be converted to TDS using the formula: EC (µS/cm) = TDS (ppm) / Conversion Factor. |
|
Advantages |
Provides a direct measure of the total dissolved substances, useful for a general overview of nutrient concentration. |
More precise and consistent for measuring nutrient concentration, as it directly measures the ionic content. |
|
Disadvantages |
Conversion to EC can vary based on the conversion factor used, leading to potential inaccuracies. |
Does not provide information on the specific types of ions present, only their total conductivity. |
|
Preferred Use |
It can be used for a general assessment of nutrient levels, but it may not be as accurate for precise nutrient management. |
Preferred for consistent and accurate nutrient management in hydroponics, as it provides a reliable measure of ionic concentration. |
FAQs About TDS and EC
To help you better understand TDS and EC, we’re going to answer several FAQs about these two important parameters.
Is TDS or EC better for hydroponics?
In hydroponics, both TDS and EC are used to measure nutrient levels in the water, but EC is considered more precise and reliable. TDS measures the total amount of dissolved solids in the water, which includes both organic and inorganic substances, while EC specifically measures the ability of the solution to conduct electricity, which is directly related to the concentration of nutrient ions. EC provides a more accurate indication of the nutrient strength because it correlates directly with the ionic content that plants can absorb. Therefore, for monitoring and adjusting nutrient levels in hydroponic systems, EC is usually the preferred method.
What is a good TDS level for hydroponics?
A good TDS level for hydroponics typically ranges from 500 to 1500 parts per million (ppm), depending on the plant type and growth stage. Seedlings and young plants generally require lower TDS levels, around 500 to 800 ppm, to avoid nutrient burn and ensure healthy root development. As plants mature, they can tolerate higher TDS levels, up to 1500 ppm, to support robust growth and fruiting. However, it's important to monitor and adjust TDS levels regularly, as different pl ants have varying nutrient requirements, and levels that are too high or too low can negatively impact plant health and yield.
What is the best conductivity for hydroponics?
Generally, the best Electrical Conductivity (EC) level for hydroponics falls between 1.0 and 2.5 mS/cm. Most plants thrive in a range of 1.5 to 2.0 mS/cm. During the vegetative stage, an EC of 1.2 to 1.6 mS/cm is ideal, while during flowering, it should be between 1.6 and 2.4 mS/cm. However, specific plants may have different requirements. For example, asparagus prefers an EC of 1.4 to 1.8 mS/cm, and blueberries do well with an EC of 1.8 to 2.0 mS/cm.
Conclusion
In conclusion, it’s important to understand what TDS and EC refer to. While TDS provides a general overview of the dissolved content, EC is more specific to the ionic strength, making it a more precise tool for monitoring nutrient levels in applications like hydroponics. Understanding the differences between these two measurements helps in making informed decisions about water quality and nutrient management.
