- Hi, this is Ethan with Bright Agrotech.
Today, we'll be talking about electrical conductivity
also known as EC.
We will talk about what EC is, how to manage it
and some troubleshooting for common problems with EC.
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- Electrical conductivity, as you might guess,
is a measure of how easy electricity
can be passed through a solution.
This is the easiest way to measure
the nutrient concentration of a solution.
The reason for that is because most plant nutrients
are available as soluble ionic compounds.
Ions basically act as an electrolyte in water
and they increase the conductivity of that solution
when they are dissolved into solution.
When you're adding nutrients to your solution,
you are effectively adding ions to that solution
which are increasing the electrical conductivity,
so the more nutrient you add the higher your EC will become.
Electrical conductivity is something
that we can consistently measure
and that is why it is such an easy system to use
for checking your plant's nutrients.
So, the EC is there to measure
how much available nutrient is in your solution.
Most hydroponic systems will being running
at a range of one to 2.5 EC depending on what you want
to grow in that system.
Seedlings, for example, will take a very low EC
because they are sensitive to that nutrient solution.
They don't like a lot of salts and you can burn them easily,
so they like a low EC.
Somewhere around one is what I typically run our setup at.
Lettuce is also typically on the low end of the spectrum.
I find that I like an EC of about 1.2, 1.4.
If you're growing just lettuce, you may have to balance
this with other crops that you have in your system.
For example, if you are growing herbs like basil,
it likes a very high EC so it likes a lot
of nutrients in the solution.
It can handle that salt content in solution
and they will prefer up on the higher end of the spectrum
around two or even a little bit higher than that.
As I said earlier, if you have multiple crops
in that system between herbs and lettuce
you're gonna have to find a happy medium
somewhere in between.
So, if you're curious as to what is actually being measured
by your nutrient meter when you're measuring EC,
it is a unit known as the siemen.
If you're measuring EC specifically,
you are measuring millisiemens per centimeter.
Which is a measure of conductivity through a solution.
Now, sometimes you might have meters that will read
in conductivity factor, or CF.
That's just a scale of 10 above,
so you're reading decisiemens per centimeter.
So, now that you have a basic idea of what EC is
we will talk a little bit about how
to monitor and manage your EC.
So, in order to measure your electrical conductivity
you will need an EC meter.
Often times these meters are made
in conjunction with your pH meter.
This a handheld unit right here
that we have, made by Autogrow.
If you are using an auto-dosing system
you will already have the pH
and the electrical conductivity probe,
included with that unit as well.
What we have here is a meter
that reads in EC, electrical conductivity.
You will also see meters that will read
in parts per million or total dissolved solids,
which is also an expression of parts per million.
Those are not ideal for hydroponic usage
because parts per million will vary from what region
the meter was produced in.
Electrical conductivity is always constant
across any manufacturer of any meter that reads in EC,
it will always be EC from one to the next
as long as it's calibrated properly.
So, these meters that are reading in parts per million,
what they're actually doing is first reading
the electrical conductivity just like this Autogrow here is
and then they are sending it through a conversion factor
in its little computer software inside there
and spitting out an approximation
of what parts per million is.
The only way to accurately measure parts per million
is to actually, completely evaporate your solution
and weight what's left.
So, obviously evaporating off your nutrient solution
and weighing the remainder is a very time consuming process.
It's not something you wanna be doing
all the time to measure your EC.
Now, another reason why these parts per millions meters
are not really the best idea is because
depending on the region the meter was manufactured in,
one EC will not always be the same
parts per million amongst these meters.
So you have a US standard, you have an Australian standard,
and there is also a European standard for parts per million.
For example, a meter produced by Hanna
that reads in parts per million,
one EC is equivalent to 500 parts per million.
A meter that is made by Utech
that reads in parts per million,
one EC will be 640 parts per million.
A meter that is produced by Truncheon,
one EC will be 700 parts per million.
Are you confused yet?
So, that in a nutshell kids, is why we like to talk in EC.
In terms of EC, it is constant.
You can talk to anyone across the world about EC
and you are always talking about the same number.
You don't have to wonder if this person's from Australia
and they're talking about a different conversion factor
with the meter that they're using.
It's always the same.
So, when we have customers that call in
and they ask me, Ethan what's wrong?
Here's what my EC is and they give me a number
in parts per million, I have to ask 'em,
who made your meter?
Now that you know how to monitor your solution
with your meter, the next step is actually adjusting
your electrical conductivity.
So, to adjust your electrical conductivity upwards,
if it is too low, you're going to want
to use a nutrient solution.
If your electrical conductivity is higher than desired,
you will want to dilute that with plain water.
If your water source has very high EC,
i.e. very high total dissolved solids
as you can find in your city's water report
you will want to be using some type of filter
like a reverse osmosis filter
to help remove those solids from solutions
so you have a lower EC starting point with your plain water.
And that's why you might want to get a filter
if you're tap water has a high EC,
just because you're adding more nutrients
to that solution when you're adding fertilizer.
If you're already very high up there
close to your set point with just plain tap water,
you're not going to be adding much fertilizer
for your plants.
You won't be adding much fertilizer
to your plants because there's already
that high mineral and salt concentration in your water,
so if you're adding a lot of nutrients to it
your EC is just going to skyrocket.
It's gonna be way too high,
so you basically have a very limited amount
that you can add to your solution
because there's these undesirable hard water type minerals
in your water.
So, to summarize, when you're adding your nutrient solutions
you are adding soluble salts to the system there.
When you're needing to dilute your solution
adding plain water will lower that concentration of salts
and thusly lower your EC.
So, if you are in a small, hobby-size system
more than likely you will only have
a single part nutrient solution.
For this, it is best to refer
to the instructions on the back.
It may say something like, one tablespoon per gallon.
As always, start on the small side
and measure often and increase if you need to.
It is a lot easier to add a little bit more nutrient
than it is to have to drain solution off of your tank
just so you can add water to dilute what you have.
Other systems may require a multi-part nutrient solution,
often auto-dosing systems do require multiple components
to their nutrient solution.
For more info on nutrient solutions,
please see our beginner's guide to hydroponics.
It is a good idea to measure your electrical conductivity
at least daily, if you have an auto-dosing system
it will do this constantly for you.
But, I would recommend for home systems at least once a day.
That is because a number of reasons.
When the plants are using that nutrient solution,
what they are doing is selective ion uptake.
They are taking those nutrients out of solution
which will drop your EC.
At the same time, plants are also using up the liquid
in that solution so if they're using up that water faster
than they're going through the nutrient solution
your EC will actually rise.
You can see a lot of fluctuation there,
it's good to check it often.
And definitely, every time you're adding water
or if you're adding nutrients, check your solution
and check again once it's had time
to circulate through your system.
Now we'll talk a little bit about troubleshooting
for some common problems that people will have with EC.
As mentioned earlier,
your starting solution of your tap water,
you might have really high total dissolved solids.
You may need a filter to get your water into a range
where you can actually start adding
your hydroponic nutrient to that water.
Other common problems that you may experience are,
reading with a meter that reads in parts per million
and not understanding which conversion factors that's using.
As we mentioned earlier in this video,
that can vary a lot between the manufacturer of the meter
and if you don't know what that relates to
in terms of electrical conductivity
you could be taking someone's recommendation
and going far above or far below,
what they actually meant for that solution to be dosed at.
Another common problem is adding too much nutrient too fast.
As I have said before, it's best to start with small doses
and frequently check your solution
to make small corrections, so you don't overshoot.
Another common problem that you will see
is not calibrating your meter.
Your meter needs to be cleaned and calibrated regularly.
If you're using an auto-dosing system
where the probes are constantly in solution
I would recommend cleaning and calibrating once per week.
If you're using a meter that is handheld
and is only in solution once per day for a few minutes,
you could probably get away with doing it
every two to three weeks.
Electrolytes, it's what plants crave.
In a roundabout way, it actually is.
While I wouldn't necessarily recommend watering your plants
with Gatorade, I hope you've learned today that EC
is a measure of the electrical conductivity of the solution.
So what you're actually measuring
is dissolved ionic salts in the solution.
Effectively, you are measuring how much available nutrient
has been dissolved into your solution when you measure EC.
We really hope you learned a lot
from this video today and enjoyed it.
If you have any stories about your particular struggles
with EC, we would love to hear about it
in the comments section below.
Also, if we forgot anything,
left anything out, or messed up anything,
please do not hesitate to let us know.
Again, I'm Ethan Walter here with Bright Agrotech.
Thank you for watching, until next time.
(upbeat music)
And that's the way the cookie crumbles.