EC, stands for “Electro Conductivity”, and is a measurement of how many dissolved salts are in your plants feed. Most growers will use EC meters for hydroponics and coco grows, but they can also be used for any medium if you’re growing with salt based nutrients.
There are a few ways to measure the EC of the feed and medium of your plants. Sometimes it can be called “TDS” which is total dissolved salts, or “PPM” parts per million”.
In this guide, we will discuss what are the best EC meters for growing in hydroponics, and why it is important to use a good reliable EC meter.
If you are having trouble deciding which EC meter you should buy, feel free to ask for advice in our cannabis growers forum
- What is EC, and How Does it Work
- What is an EC meter
- Why EC is Important When Growing Cannabis
- TDS, PPM, or EC
- How EC Meters Work
- Best EC Meters for Hydroponics
- How to Test the EC of your Feed
What is EC, and How Does it Work
When growing cannabis hydroponically, you will tend to use what is known as “Salt based Nutrients”. These are chemically made plant nutrients, and everytime you add some to water, it will increase the electro conductivity of the liquid.
The more salts that are dissolved in a solution, the higher the EC will be. This is a great way to find out how much you are feeding your plant, and if you’re feeding too much, or not enough.
Monitoring the EC of your feed, will give you a good insight into how much your plant is eating, and it can be crucial to keeping a cannabis plant healthy.
To measure the EC of a nutrient solution, you will need an EC meter. These are similar to pH meters, but of course they read EC rather than the pH, although, there are models you can get that do both.
What is an EC Meter?
To put it simply, EC meters for hydroponics are devices that will detect the amount of nutrients in your water, by sending an electric current from one probe, through the water, to another probe.
This will give you a reading of how conductive the liquid is. The more salts that are dissolved in the liquid, the higher the EC will be.
The probe of an EC meter is placed into the water you are testing. After a few seconds, it will give you a reading, for example, 1.0. This means the EC of your solution is 1.0, if you were to add more nutrients, the EC will rise, if you were to add more clean water, it will fall.
EC meters will need calibrating after long periods of use to keep them accurate. You should always rinse the prongs after every test, this will increase the lifespan of the EC meter, and improve the reliability of the device too.
There are many makes and models of EC meters for hydroponics you can buy online. But a lot of them are cheap, and unreliable. When you are testing the nutrient solution for your cannabis plants, you want to be certain that pH and EC are at the correct levels. This will keep your plants happy and healthy.
It might be tempting, but do not buy cheap EC or TDS meters. In this guide there are models that are recommended by growers who have used them before. They are trusted, reliable brands, with a good reputation. They might be a little more expensive, but it is worth it for the peace of mind.
Why EC is Important When Growing Cannabis
Growing cannabis is a great hobby, but it can soon become stressful when things start to go wrong, and you do not know how to fix it.
Cannabis plants can easily suffer with nutrient excess and deficiencies. Monitoring the EC will reduce the chances of this happening, and will help keep your plant healthy, and growing happily. It will also reduce the stress of growing, and make the hobby more enjoyable for you.
By monitoring the EC of the feed going in, and the runoff coming out of your medium, or monitoring EC levels of your reservoir, you will be able to judge whether the plant is being under fed, or overfed easily.
Here is an example:
You mix up your nutrient solution:
2ml of Canna Rhizotonic
1ml of Canna A
1ml of Canna B
You use your EC meter to check the EC of the solution, and it reads 0.8
Now, you will feed your plants with that solution at 0.8.
When you feed the plant next, you will collect the water that comes from the bottom of the pots, known as run off. If you are using a recirculating reservoir, or DWC, measure the solution in the reservoir.
If the EC is lower than 0.8, then your plant isn’t being fed enough and you should increase the EC of the nutrient solution by 0.2 points for the next feed.
On the other hand, if the EC has risen, then your plant is being fed too much, and you need to reduce the EC on the next feed.
You can read more about EC fluctuations in hydroponics in our guide here:
After a few tests, and a few feeds, you will have found the perfect level for your plants diet. You should continue at this level, and monitor the EC, and if it starts to fall, you can feed your plant a little more.
Monitoring the EC will give a good insight on what your plant needs. This will reduce the chances of nutrient deficiencies, and stress on you, and your plants.
TDS, PPM, or EC
You may have heard about other types of meters for hydroponics that can read the level of nutrients in a solution. These can be called PPM meters (Parts Per Million) , or TDS Meters (Total Dissolved Salts).
These meters can be less accurate than EC meters for hydroponics , and for PPM, the readings will have different conversion ratios depending on the manufacturers.
This will depend on which country the meter is from, and will be either; 0.50, 0.64 or 0.70. To find out which conversion method a particular PPM meter uses, you will have to check with the manufacturer, or it may be in the instruction manual.
This causes confusion, and your readings will be unreliable.
EC meters are used by cannabis growers, because they are very accurate, with no need for any time consuming conversions. No matter what country you are in, the EC reading does not change like a PPM meter does.
It is recommended to only use EC meters. They are more relabie, more accurate, and are very easy to read.
If you do have a PPM meter, you can find out which conversion ratio it uses (0.50, 0.64 and 0.70) and then convert it to EC for a more accurate idea of what is in the solution.
PPM to EC Conversion
To convert your PPM readings to EC, you first need to find out what conversion ratio your meter uses.
This will be either 0.50, 0.64 or 0.70, refer to your instruction manual for which one you should use.
Once you know what conversion ratio your PPM meter uses, you can use this chart below to convert it to EC, or vice versa:
How EC Meters Work
An EC meter for hydroponics have two probes, that are made of a conductible metal. When these probes are inserted into a solution, one probe, will send an electric current to the other.
When a solution has a low amount of dissolved salts in it, the electrical current will pass through the fluid at a slightly lower speed than it would in a solution with a high amount of salts.
It takes a few seconds for an EC meter to give you an accurate reading. You simply dip the probes into the water, and wait. Do not stir, you should keep the EC meter still for an accurate reading, the solution should be well stirred before testing it.
Over time, the prongs on an EC meter will build up salts from numerous tests, and they need to be recalibrated and cleaned. It is good practise to clean and calibrate your EC meters monthly. But this will depend on the amount of tests you do in that time, and how clean you keep the meter.
Best EC Meters for Hydroponics
When you look online for EC meters for growing cannabis, you will come across many brands and models. Some of them can be very cheap, and you may be tempted to buy one of those.
It is important to have a quality EC meter, so you can be sure the readings you are getting are reliable and accurate.
The three main brands that cannabis growers will use for their EC meters in hydroponics are, Essentials, Bluelab, and Hanna. Do not go with any other brand, these guys are tried and tested, and are respected brands amongst the growers community.
They may cost a little more than the cheaper models, but the extra cost is worth the piece of mind that you know for sure you have a good reading of the EC of your nutrient solution.
Essentials are a great budget brand for EC and pH meters for growing cannabis. They are precise, and will stay accurate for up to three years!
If you keep your Essentials EC meter clean, and wash it after testing, you will extend its life span, and it will stay accurate for longer.
Here are some features the Essentials Ec meter has:
- Accurate and rapid EC measurement
- Water resistant, shock and drop proof
- Energy saving shut-off and battery warning
- Minimum lifespan of about 1 to 3 years depending on the rate of sampling
- Digital calibration at the push of a button and a lit screen for when under dark foliage
This EC meter is cheap, easy to use, and reliable! It is trusted and used by many cannabis growers, and you can be sure you will not be disappointed with this model.
Bluelab are one of the top brands when it comes to EC and pH pens. They are very accurate, and not only measure the EC of your nutrient solution, but it also measures the temperature.
This particular model of EC meter, will also change between PPM 50 and PPM 70, so if you do prefer growing with PPM, then you have that option, along with increased accuracy.
Easy to calibrate and easy to clean, if you look after the Bluelab EC meter, then it will last for many years.
Calibration is also easy, with just a press of a button this model is ready for calibration.
Here are some of the features the Bluelab EC meter has to offer:
- Digital readout of the conductivity of your nutrient solution
- Compensates for temperature for improved accuracy
- 4 scales to select from – EC, CF, PPM50 and PPM70
- Backlit display
- Hold reading function
- Simple to use
- Simple calibration process with 30-day indicator
- Low battery indicator
- Displays the temperature in ºC or ºF
- Water resistant
- Shock resistant
- Automatic power-off to conserve battery life
If you are serious about the diet of your plant, and keeping good track of what it needs, then a Bluelab EC pen is perfect for the job. A little pricey compared to Essentials, but with the added extras, it’s worth the investment.
Hanna only do quality equipment. Some of their EC meters for hydroponics and pH pens can cost hundreds!
They are very trusted in the cannabis growers community.
This is one of the lower end models, that is good for Percy Growers. You will have the accuracy of a professional EC meter, for a hobbiest price.
It will adjust for temeprature, to give an accurate reading that you know is reliable. Hanna also offer a service where you can send the EC pen to them for recalibration when it is needed. But these EC pens can stay arrucate for hundreds of tests before they need recalibration.
How to Test the EC of your Nutrient Solution
After mixing up your nutrient solution with the required dosage, you should check the EC before feeding your plants.
Before testing the nutrient solution, you should stir it well, and let it sit for a few minutes. This will allow the salts to disperse, and give you a more accurate reading.
EC meters for hydroponics all work in pretty much the same way. You simply remove the cap, and turn the meter on with the press of a button. It will usually take a couple of seconds to load up.
When the EC meter has turned on, you will insert the end with the 2 prongs, into the nutrient solution, but do not fully submerge the whole EC pen.
Only the prongs need to be in contact with the water, so there is no need to fully submerge it.
If you are growing in a hydroponics system with airstones, you should turn them off, to make sure no bubbles are interfering with the test.
After a few seconds, the pen will “beep” and your reading will be shown on the screen, as a digit, with one decimal place, for example, 0.8.
It is best to rinse the prongs of the EC meter after use, this will remove left over salts, and prolong the accuracy and life span of the EC Meter.
What is Background EC
When you use tap water, there is likely to be certain minerals added to it. Though this is just water with no plant nutrients added to it, these minerals will be picked up by your EC meter. This is your background EC.
Background EC will differ massively depending on where you are in the world, and the quality of your water. Most of the time, background EC will be below 0.3 EC but this is still counted towards your overall EC.
In some cases, BG EC might be as high as 0.8! This is very high, and if you test your water to find a background EC as high as this, reverse osmosis may be a good option for you.
The saying goes, buy cheap, buy twice, and that applies here. There are many models you can buy, but you want god reliable equipment so you can have peace of mind that your reading are correct.
Get a good EC meter, look after it, and calibrate often, and you will find it easier to keep you plants eating correctly.
Thanks for reading our guide on EC meters for hydroponics! Stay safe, and happy growing, dont forget, if you need help with your grow, or would like to join our community, come and sign up! It would be great to have as part of our forum.