Pioneering Hydroponics

Since 1976

Guide to EC Levels in Hydroponics

What is EC?

An electrical conductivity meter (EC meter) measures the electrical conductivity in a solution. It is used in hydroponics to monitor the amount of nutrients, salts or impurities in the water.

EC and pH levels go hand-in-hand in hydroponics. pH is the measure of acidity/alkalinity of a solution and is important as it affects the solubility, availability and uptake of several of the essential plant nutrients.   On an interesting side note; it also affects microbial and enzymatic activity! Knowing the pH level of the nutrient solution and grow medium is also vital. When pH levels are too low or too high, plants can’t get the correct nutrients in the right amounts. The ideal pH level in hydroponics is between 5.5 and 6.5.

pH provides insight into the nutrient balance of your nutrient solution and EC levels provide an indication into the quantity of nutrients available in the solution.

EC gives you an overall level of nutrient concentration - it measures the total dissolved salts/solids  in the nutrient solution. You can also measure TDS (total dissolved solids) with a TDS meter which measures the content of substances in any liquid. Both EC and TDS measure concentration of salts, solids and impurities but have different units of measurement. The higher the concentration of salts dissolved in water, the higher the EC. The more diluted the nutrient solution, the lower the EC.



How Does EC Affect Plant Growth?

When the EC level is too high, which translates to how strong the solution is, it will cause nutrient burn on delicate plants and seedlings. The concentration of the nutrient solution can be increased for the vegetative stage   according to the type of plant you’re growing.

For a grow room with a mixture of plants, you’ll need to separate them into heavy feeders, medium feeders, and light feeders if you have them. With every feed rate, you’ll need a separate reservoir.

As an example, feeding lettuce with EC levels suited for tomato plants’ needs will result in the former being bitter. On the other hand, feeding tomatoes with EC levels suited for lettuce needs results in the tomatoes having no taste.  If different plants aren’t split up this can also result in them being over or underfed.

EC will also change dependent on how fast a plant is using the nutrients. If nutrient uptake is high, then EC will drop quicker.

For most plants you want the EC measurement to be between 0.8-1.2 during the vegetative stage and 1.4-1.8 during flowering, but this is a guideline as it depends on the type of plant. 


Do Water and Air Affect EC Levels?

Nutrient solutions should have temperatures between 18℃-21℃,   as plants don’t like when water temperatures change rapidly. This is particularly vital around plants’ root zone, so make sure that any water you add to the reservoir matches its temperature.

You also need to account for ambient temperatures; warmer climates may require chilling options for the nutrient solution and colder climates may require a heater.

Ventilation and airflow also affect EC levels. With ventilation, you’re discarding old air and introducing new air, and with airflow you’re moving the same air. Better ventilation will result in higher transpiration rates, which leads to plants increasing their nutrient absorption and intake rates.  This also applies to CO2 supplementation.


What Should You Do When EC Levels Change?

If EC levels increase and:

  • pH also increases, lower the EC by 0.2.

  • pH decreases, change the reservoir and lower the EC.

  • pH doesn’t change, lower the EC by 0.2.


If EC levels decrease and:

  • pH increases, raise EC by 0.1.

  • pH also decreases, change the reservoir and raise EC by 0.2.

  • pH doesn’t change, raise EC by 0.2.


If EC levels don’t change and:

  • pH increases, this is normal and you should continue growing as you are unless the level changes by more than 0.5. Should this occur, you need to change the reservoir and re-feed at a lower EC level.

  • pH decreases, change the reservoir and lower EC.

  • pH also doesn’t change, this is perfect!



What if the EC Levels Change But the Water Levels Don’t?

EC levels increase and:

  • pH also increases, raise the EC as plants are leeching certain foods.

  • pH decreases, change the reservoir and increase EC.

  • pH doesn’t change, raise EC by 0.2 as plants are leeching certain foods.


EC levels decrease and:

  • pH increases, change the reservoir and lower EC.

  • pH also decreases, lower EC or change the reservoir.

  • pH doesn’t change, lower EC by 0.2 as plants are eating but not drinking.


EC levels don’t change and:

  • pH increases, lower EC by 0.2.

  • pH decreases, change reservoir and readjust levels.

  • pH also doesn’t change, lower EC by 0.Controlling EC levels in hydroponics is essential for strong and healthy plants. We advise that you measure EC every day so you can keep an eye on the levels and deal with any problems as soon as they occControlling EC levels in hydroponics is essential for strong and healthy plants. We advise that you measure EC every day so you can keep an eye on the levels and deal with any problems as soon as they occur.

 

Controlling EC levels in hydroponics is essential for strong and healthy plants. We advise that you measure EC every day so you can keep an eye on the levels and deal with any problems as soon as they occur.