[Sticky] What is EC, and How Does it Work?
What is EC, and how does it work. This is a common question for new growers, especially if you are thinking about growing cannabis hydroponically. When growing in hydroponics, or mediums like coco, it is common for growers to use “salt based nutrients”. These nutrients, when added to water, will change the EC (electro conductivity) of the liquid.
This means, electricity can pass through the water easier, by moving through the salt particles. This essentially, is what EC is. By measuring the conductivity of the water, you can tell how much food is in it.
When you first test the water coming out of your tap, you will find it already has reading on your EC meter, before you have added any nutrients.
This number will be known as your “Background Ec”, and will count towards the food your plant is receiving. Always include it as part of your feed, as it is still food to the plants.
If you have any questions about EC, and how it works, then feel free to ask us anything in our cannabis growers forum
How to Monitor Your Feed With EC
In this example, we will say, your water has been tested and the reading is 0.2. This is good, there is very little contaminants in your water.
The instructions on your nutrient bottle will always give you a set dose. It will probably be way too high. Cannabis eats far less than most plants, and over feeding it can cause nutrient deficiencies and excess. It is much easier to fix an under fed plant than an overfed one. Be very gentle with the food.
Ignore what the bottle says, and add your food to the water, until the EC is 0.2 points higher than you BG EC. In this example, the reading would now be 0.4
You may have only added 0.5ml per litre of your food, but this is all your plants will need whilst they are young. Increasing the E.c by 0.2 points in increments, and monitoring the run off or reservoir, you will know exactly what your plant is eating.
Check What Your Cannabis Plant is Eating
Let's say you have fed your plants for a few days with the EC of 0.4, and check the run off or reservoir to find it has dropped to 0.3. This means your plant is eating more than you are giving and it would be happier to bump that EC up by 0.2 points, so in this case the reading will now be 0.6.
After a couple more days feeding at 0.6 check the run off again. If it comes out lower than 0.6, increase the EC of your food again.
- If the Ec of your run off, or Res falls, raise the EC of your next feed.
- The EC Rises, reduce the EC of the feed.
- EC is stable, keep the feed balanced at the EC.
By following those simple steps, you can feed your cannabis plant exactly the right amount of food. As long as your PH is in the right range, you plant has all the nutrients it needs to grow healthily and happily.
If you have overfed your plant, and you are experiencing symptoms of excess nutrients, then flushing you medium, or changing the reservoir, will fix the problem. Then continue feeding, but at a lower EC.
How to Fix an Overfed Cannabis Plant.
If your plants are overfed for too long they will develop a salt build up. You need to flush your medium, and reduce the next feed by at least 0.2 points. This should restore balance to the medium, and you should keep with this EC. When the plants start to look hungry ( Light green/ pale), then you can increase the reading by 0.2 points again.
It seems like small changes, and small doses of food, but you will find that the plant will eat less, but often, and be much healthier. An under fed plant is much easier to fix than an over fed plant.
Many growers will tell you, less is more. Keep the EC low, and the feeds coming often, and your plants will eat healthy their whole lives. Less food will bring you sweet, rich flavoured buds, that are clean, and not full of dissolved salts.
The Best Ec Meters for Growing Cannabis
EC is a very important aspect of your plants diet when growing in hydroponics and coco. Because of this, you need good, reliable meters, that your know for sure, are giving you accurate readings. Only go with what is recommended HERE. Don’t cut corners with your equipment, your plant will thank you for it.
Thanks for reading! You can find more information on anything related to growing in our cannabis grow guides. All of our guides are written by experienced growers, and members of our cannabis growers forum. If you have any questions, sign up. It is free, and we are always happy to help!
Much love Percy Growers, Happy Growing!
tnx for the info
Percy good article! I am mixing soluble fertilizer to get to correct EC/PPM; Water is hard 350ppm so I RO.
Will the plants split the compounds from salts and take the n-p-k and reject the unused ion compounds back to reservoir? Like potassium K2O. Plant breaks it down to get the K and then oxygen combines with something and goes? What I am asking does the reservoir build up with unused salts and should reservoir be drained?
@terrapin Any nutrient that isnt used will stay in the water until it is drained away or used by the plant mate. It always good to clean the res and give fresh feed once a week
Thanks! Do you know of any articles on reservoir sizing based on plant numbers for indoor grow arid climate?
Exactly what I needed to know.. thanks guys
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