WHAT IS EC:
EC or electrical conductivity is a measurement of how much electrical activity is in your soil / substrate at any given time. We know that water can conduct electricity. Well, that's not totally true. Distilled water can't conduct electricity at all. It has been stripped of all minerals. Highly mineralized tap water can conduct electricity like copper wire. Adding nutrients to your soil increases EC. Growing in artificial substrate like rockwool could have a zero EC level depending on how it's made.
Natural soil has plenty of minerals and when enough water is supplied EC levels can be easily checked using a high quality sensor like the AROYA SOLUS. Retail potting soils have a wide range of minerals which are added during mixing and will have an entirely different EC level when water is added.
AROYA SOLUS at work
WHY EC MATTERS:
EC is important because it helps us understand the level of nutrients and fertilizer, in addition to what was already in your chosen grow medium. Too many nutrients will block your plants ability to absorb water through the roots. Symptoms include yellow and brown leaf tips and curling. Not enough nutrients allows the plant to absorb water without the ideal level of nutrition to maximize growth rates. This often shows up as leaves yellowing.
THE GUESSING GAME:
Most of us have had times when we can't figure out why the plants are struggling. Too much water or not enough? Too much nutrients or not enough? If we wait too long to solve the problem the plants can become permanently stunted. Nothing is more frustrating than having to kill plants because we guessed wrong about the symptoms.
EC is measured using a tool that measures water content, and what's called water potential in your soil. We'll skip the deep dive to avoid nap time. In a nutshell the EC level in your soil increases as the soil becomes drier. And it decreases as the water is added. This is because there is less water to conduct the electricity through the minerals.
Freshly saturated 6 x 6 rockwool blocks (screen grab from AROYA SOLUS App)
All of us care about light levels. Most of us have PAR measurement tools so we know what we're providing to the plants. Tools like the AROYA SOLUS are just as vital as a PAR meter. Seedlings require a different level of EC versus Veg plants versus Flowers.
Coco, living soil, potting soil, all have different speeds of drying out after a full dousing of water. Fabric pots air out faster than plastic pots and so on. The image above shows a 1.87 EC level 20 minutes after fully saturating a rockwool cube and was 80% water content. The moisture content level will slowly go down as the water drains off, evaporates or the plant takes uses it. The EC level will rise during the dry back phase. Between these two variables the ideal EC level can be maintained.
THE RIGHT EC:
The Ideal EC level for cannabis seedlings and young veg plants is around 0.5 - 0.8 until around 12 to 14 days after germinating. This should be progressively increased to 1.1 towards the end of the growth period. During flowering stage plants need more nutrients. EC should be between 1.2 and 1.5, keeping it there until the fattening period, where you should increase it to 1.8 / 2.1. Higher EC levels than 2.5 are known to reduce crop yield. The baseline you choose can be set initially by measuring EC during dry back. Soils and grow mediums dry back at different rates and also based on plant size.
Ideal EC levels for growing, courtesy of Cannabis Business Times
The baseline you choose can be set initially by measuring EC during dry back. Soils and grow mediums dry back at different rates and also based on plant size. If we allow the soil to dry completely EC levels won't be readable as there is no salinity for the electrical current to travel in. If we measure EC right after watering the SOLUS will read very high moisture content and low EC. Choosing your idea EC target will come from spot measurements during dry back. We like to do a screen capture of the readings on our phone since the SOLUS does not record data. We put these into their own folder on the phone. It's cool to see the progression visually. And the time stamp is on top of the image.
To increase EC levels we increase the amount of water with nutrient feed. And wait for the ideal time we've picked as the soil dries back. Decreasing EC is a matter of adding just water which will wash away the larger minerals and nutrients from the soil and reduces EC when measured at the same amount of time during dry back.
In this way we can establish what EC levels our plants thrive in. And we can consistently measure to an ideal standard EC level.
We like the AROYA SOLUS because it is easy to use, portable and highly accurate. The App is simple and its easy to understand the readings.
Just like PAR meters, the SOLUS is a spot measurement tool, Personally we don't have the time to crunch data from software. We like simplicity because we'll use it more often.
For our needs the SOLUS is great. We just take spot measurements as we transition to any new soil medium, nutrient mix or when we change the watering schedule. We know our water minerality isn't going to change much. So it's all about the quantity of water and how fast or slow we apply it and how the nutrients are building up in the soil or washing away. Once we have that nailed down we just take spot measurements occasionally and if we see any negative growth symptoms developing we get right on it with the SOLUS.
Every serious grower should own an AROYA SOLUS as well as a good PAR meter like the Apogee MQ-500. These tools are indispensable and will both save crops from accidental mismanagement. The cost is well worth it.