Rather than absorbing plant nutrients from the soil, hydroponic plants take up dissolved minerals in fresh water. They generally obtain their nutrient requirements in an inorganic form. Because of this, growers must maintain proper electrical conductivity or molar conductivity and pH levels to grow healthy hydroponic plants.
A range of 1.5 to 2.5 dS/m is ideal for EC for most hydroponic crops. Plants experiencing increased osmotic pressure might be unable to absorb nutritional salts, and EC levels that are too low could adversely affect maximum yields. Let us discuss the importance of EC level for hydroponics and maintaining it. We will discuss several common hydroponic crops in addition to the EC values.
What is EC?
Hydroponics calculates electrical conductivity (EC) based on how easily electricity passes through the solution. The conductivity factor (CF) measures electrical conductivity in millisiemens per centimeter (mS/cm). Soluble ionic compounds are the most common form of plant nutrition. Charged particles are ions. You will achieve increased EC by adding more of these charged particles.
Units of EC
It is important to know how to translate your EC readings obtained from your nutrient solution so that you can interpret them correctly. The electrical conductivity is typically expressed as a siemens per unit area. When one volt of electric potential is applied across one meter of nutrient solution, the electric current through the solution increases by one amp for each unit of one S/m conductivity.
EC readings can be expressed using different metric prefixes. A unit of measurement called mho, the reciprocal of an ohm, can be used instead of siemens. A siemen equals one mho.
Converting EC to ppm
An EC measurement indicates the amount of electric conductivity in a substance, as described previously. Hydroponics involves dissolved nutrients made up of ions. Therefore EC is often used to determine total dissolved solids (TDS). Parts per million (ppm) are the units of TDS measurement, which indicates the concentration of nutrients in the solution.
Electrolytic conductivity is converted to TDS according to several standards around the world. Conversion factors vary between EC meter manufacturers and understanding this is crucial. It is crucial to read the instructions of your ppm meter to determine which conversion factor is to be used.
As a result, these standards need to be kept in mind when interpreting advice presented in blogs and books since different countries will use different factors.
EC Ranges By Hydroponic Crop
Every plant has a preferred optimum range for EC because they require different types of nutrition. EC levels are affected by the amount of nutrients in the nutrient mix.
A plant’s stage of development also influences the level of EC. Since they burn easily, seedlings during vegetative growth prefer nutrient solutions with less nutrient strength. Growing more mature plants requires an EC solution with a high nutrient concentration. A low EC can minimize fertilizer costs, while a high EC will reduce changes in nutrient ratios.
Additionally, environmental factors such as air temperature affect the EC. For example, the plant’s photosynthesis rate should be reduced when the ambient air temperature reaches 86°F (30°C).
The Effect of EC On Plant Yield
How does plant growth with EC ranges that are above or below optimal affect plant yield? Study results show that tomato yield increases as EC increases from 0 to 3 dS/m of nutrient solution. As the EC was increased from 3 to 5 dS/m, the yield decreased. Researchers found that tomato yields were higher when EC levels were between 1 and 3 dS/m, depending on the growth phase.
Symptoms of Too Much EC
Ironically, it is the symptoms of nutrient deficiencies in conventional growing systems which signal high nutrient levels. Hydroponic systems with excess magnesium look just like those with calcium/magnesium deficiencies.
Nutrient toxicity may indicate several problems, listed below.
- Wilting leaves and stems
- Burned tips (nutrient burn)
- Slowed growth
- Falling leaves
Most of these symptoms may also mean other problems such as disease, inadequate water, excessive heat, or too much light. If your EC is too high, dilute your nutrient tank with a fresh batch of reverse osmosis water or distilled water. As you add distilled or de-mineralized water to your hydroponic reservoir, take measurements intermittently until the EC is back to the appropriate concentration of salts.
Measuring Your EC
The average daily water loss in a hydroponics system ranges from 5% to 30%. This depends on the size of the setup and the type of plants you are growing. This water loss results in a hydroponic nutrient solution with a high EC. This means you should measure the EC of your system on a regular basis.
Choosing EC Meters
EC meters come in a wide range of prices. What kind of features should you look for in a digital meter? The best truncheon meter will be waterproof, have an indicator for how long the battery will last, be easy to use, have an automatic shutoff, be shockproof, and be easy to calibrate. Apera, Bluelab, Hanna, and Essentials are the most popular EC meter brands.
On Amazon, you can find TDS meters that convert EC to TDS (ppm) automatically. A pH meter is often included and is very affordable (a price range of $15-$30). You might benefit from an inexpensive TDS meter if you are starting in hydroponics.
It is important to keep in mind that cheaper TDS meters are not always as accurate as some more expensive EC meters. EC measurements will be converted to ppm using different conversion factors. Comparing the measurements you take with those outlined in journal articles or blogs; can cause even more confusion.
Bluelab’s PENCON conductivity pen ($70) is a popular and somewhat more expensive pocket tester. It automatically adjusts the readings for temperature changes based on the conversion scales you select. It is available on Amazon and eBay.
EC meters of higher quality are needed in large grow rooms. The Bluelab BLU27100 Guardian Monitor is an example of such a meter. With this monitor, you will be alerted if your EC drops below or rises above the appropriate level of nutrients. It costs from $300 to $400.
Calibrating and Cleaning EC Meters
Nutrient salts build up on your EC meter if you use it consistently. If mineral salts build up on your EC meter, they will skew the readings and shorten the meter’s lifetime. Therefore, calibrating your EC meter before taking readings is necessary. Additionally, you should clean your meter after each use.