There were a few things that were intimidating to me when I start dabbling with hydroponics. Electrical conductivity, or EC for short, was one of them. While not an important measurement in aquaponics, EC is very important to hydroponics.
What is Electrical Conductivity (EC)?
In simple terms, the EC level of your hydroponic nutrient solution lets you know how much fertilizer is in the water, the strength of the nutrient solution.
Most hydroponic nutrients (non-organic) are salt solutions. Salt is an electrical conductor, the more salt (nutrients) that is added to the water the more conductive it becomes. When an electric current has applied to the solution, the strength of the current lets you how much salt (nutrients) is in the water.
How The Water You Start With Effects Hydroponic EC Measurements
Tap water contains various minerals like sodium and chloride. This means starting out it will already have an EC level before adding nutrients. It’s important to measure the EC of the water you’re using beforehand and factor that into your reading after adding nutrients.
Pure water has an EC of zero because there are no mineral ions in the water. While not necessary, filtering your water can save work, time, and money. The only way of making sure your starting with pure water is to use a reverse osmosis (R/O) filter to filter the water before use.
Measuring EC Of A Hydroponic Nutrient Solution
Measuring the EC level of your nutrient solution is easy with an EC meter. Like the one shown below.
There are a couple of different ways you can measure hydroponic EC. There are:
Parts per million (PPM)
Millisiemens per centimeter (mS/cm)
I would recommend using millisiemens when measuring the EC of your nutrient solution for a couple of reasons. PPM is a measurement also used when measuring total dissolved solids (TDS) which can cause some confusion. Also in many popular books, research, and in larger operations, millisiemens is the more common measurement referenced.
Measuring the EC level of your nutrient solution is as simple as using a meter like one shown below.
You should calibrate your EC meter regularly to make sure it is giving you an accurate reading. The desired hydroponic EC level depends on the type of plant your growing and the stage of growth it is in. Plants tend to do better with a lower EC during the vegetative stage compared to the flower and fruiting stages.
How You Can Utilize EC Levels Of Your Hydroponic Garden
Prevent Over or Under Fertilizing– More fertilizer does not equate to faster or larger growth. Too much fertilizer in the vegetative stage actually stunts the growth. If you notice EC levels are high, add some water to dilute the nutrient solution.
If EC levels are too low, there aren’t enough nutrients in the water for the plant to take in to reach its full growth potential. You will need to mix up some nutrients and top off your reservoir or empty and do a complete solution change.
Increase Production of Antioxidants– Although it can have an effect on the size and amount of fruit produced, raising EC levels can cause produce to create more antioxidants.
Increase Water Availability– Lowering EC levels on a hot day can increase the amount of water the plant is able to take in.
Some Things To Keep In Mind When It Comes To Hydroponic EC
Measure EC Levels at consistent pH levels. Measuring at different pH levels will give you different results.
Plants do not take in all nutrient at the same rate. Over an extended period of time, topping off the reservoir could cause a build-up of some minerals.
Plants do not consume nutrients consistently at the same rate. There are many variables determining how much nutrients your plants will take out of the nutrient solution so it’s best to measure the EC of your nutrient solution on a regular basis.
TDS meters can be used to measure EC. The reading from the TDS meter has to be converted into an EC reading.