A Beginners Guide: pH in Hydroponics

A Beginners Guide: pH in Hydroponics

September 14, 2019 42 By Ewald Bahringer


– Hi, this is Ethan with Bright Agrotech. Today we’ll be talking about pH. We’ll give you a brief introduction on what it is. We will tell you how do manage pH. And also offer some troubleshooting
tips in relation to pH. (upbeat instrumental music) pH is a measure of how acidic
or how basic a solution is. Acidity means a pH below that
of seven, which is neutral. Basic means a pH above seven. pH scale runs from one to 14. pH by definition is a
logarithmic measurement of the hydrogen ion
concentration of a solution. What that means is
you’re measuring the H+, which is a positive ion, or OH-, which is a
negative ion in solution. One is acidic, one is basic. Most hydroponic systems will require a pH somewhere around 6.0 to 7.5. I have found that 6.0 to
6.5 is a really nice range for most herbs and greens. So why is that pH range,
maintaining a nice stable range, somewhere between 6.0 to 7.5 necessary? That is due to the fact that
availability of the nutrients in your hydroponic
solution will vary with pH. If you go too high or too low, you might lock out certain nutrients. And you’ll see deficiencies
within your plants and slowed growth, not a good thing. So if you keep it right
at that happy medium, your plants will be happy and
get most of what they need. A little bit of pH flux can
sometimes be a good thing because it gives them a small
variance in what is available. So various crops will
have varying nutrient and pH requirements. So some crops will be
very high pH requirement, most however tend to be on
the acidic side of things. If you’re looking to find
good information on that there is tons of peer reviewed research on which crops like which pH online. You can also refer to Upstart University for this information. So how do you manage pH? First to manage pH you’re going to need some way to monitor it. So what we have here is
a hand-held pH meter. This also will read nutrient
concentration as well. But you do need to monitor your pH, monitor it daily, it will
change and fluctuate. We also have other varying
methods to monitor pH, including auto-dosing systems which will hookup to your main reservoir and dose for you from a reservoir or tank of pH Down. We also have old-school
litmus style tests, which is a strip of paper
that will change color depending on what the solution pH is when it is exposed to that solution. So if you have an auto-doser or a hand-held nutrient meter, you will need to calibrate it for pH as well as EC if
it has that functionality, but that’s a story for a different video. To calibrate your meters you will need a calibration standard. This is something that is
very exactingly produced and it never changes,
it is always pH of 7.0. Sometimes these will have
expiration dates on it, so be mindful of that. Typically you will need a 7.0 and a 4.0 to calibrate your meter. Most calibrations are
pretty quick and simple, your meter will have instructions on it. It is also recommended to
get Probe Cleaning Solution, if you have a dirty probe,
it will not read correctly. This stuff goes a very long way. So, as far as what really works
for these testing methods, the best ones are a
reputable hand-held meter as well as an auto-dosing system. However the price of these
may put them out of range for most home growers and
it may be necessary to use an old-school style strip kit. Strip kits are not the most accurate, there’s a little bit of
personal perception involved in what color you
actually see on the strip. So it can vary a little
bit in what you’re reading but it’s better than doing nothing. You do want to buy a meter
from a reputable brand. Brands like Autogrow, brands
like Hanna Instruments, Oakton, Blue Lab, they all
make reputable products, don’t just go and buy the
cheapest thing on Amazon because it more than likely
will not work very well or for very long. So adjusting pH. Once you’ve got a way to monitor your pH, you can actually take
steps to adjust your pH. Now depending on what
you do to adjust your pH, will depend on the pH of
your starting solution, I.e. what is your tap water at when it’s coming out of the tap? Here in Laramie our pH,
we are fairly lucky, it’s close to neutral. So we wind up using pH Down frequently. It will vary from season to season, so it’s good to check
your tap water regularly. Right now ours is currently at about 6.8, so we use pH Down to reach a target pH of about 6.0 to 6.2. If your water is lower
than neutral and acidic coming out of the tap you
will want to use pH Up. There are other various
methods to raise and lower pH other than store-bought pH Up and Down, however I do recommend using these because they will not alter other aspects of your nutrient solution and they are a constant solution so they will always be the same every time you purchase it. So for example, you may think that if you have an
acidic tap water source you can take just about
any base to raise that. You might want to take sodium bicarbonate, something like that, even
lye, something that’s high pH, that would be a bad, bad idea. A lot of times this can
be harmful for the plants, it can be harmful for the microbial life in your nutrient solution and is just generally a bad idea because a lot of times these methods can change the electrical conductivity of your solution as well. So once again, I recommend
using a constant, store-bought solution, this
will always be the same stuff no matter where you buy it and you can always add the same amount as long as you’re sticking
to the same brands, usually even between brands,
they’re very, very similar. One major reason to do this is you’re not going to
save a whole bunch of money by using a household product
to lower or raise your pH unless your pH of your
water is very extreme it will take very, very
small amounts of this to change your pH. Even in our medium-size test farm, we go through very small amounts. A gallon of this will last for months here and we are dosing a 300
gallon reservoir with this. So when it comes down
to actually adjusting pH I cannot recommend
auto-dosing systems enough. pH can be difficult to adjust for someone who’s not experienced in it. By and large because this is
very concentrated solution, so a very small amount
can go a very long way. As I said we use a 300
gallon reservoir in our farm to dose a brand-new solution and take it from a roughly neutral pH of tap water that we have here, it takes only about a
cup or a cup-and-a-half to bring it down. So as I said, a gallon will
last quite a long time. If you’re at a very, very small reservoir, you know under 20 gallons, you might want to start with a teaspoon, let it circulate through your system, check it again, always be checking your pH. If you’re doing it manually and
trying to adjust it manually check, check, check,
because it will change. It will change frequently. If you are using pH Down
in an auto-dosing solution, that means you are drawing your pH Down from a reservoir with your auto-doser. I recommend starting on the low side when filling up that pH Down reservoir because we have actually experienced some situations where if you
get that solution to acidic and you put in too much of this, you will get acidophilic bacteria growing inside your pH Down reservoir which is not a good thing. However, your mileage may vary and you may not have to worry about that if you’re adding pH Up. So since pH Down can be
hard to adjust manually, I actually do not try and mess with it. For our small reservoirs,
typically speaking, reservoirs that are
under 50 gallons or less, the reason for that is our tap water is usually
right around neutral, right now this time of year, we’re reading about 6.8. So we’re already pretty
close to that range that’s good for plants. Now if you add nutrient solution, usually nutrient solution
is a little bit acidic, so that will slightly
lower your pH as well. So we get a little closer
to that mid-six range that’s really nice. Plants also do a thing
called selective ion uptake. As we mentioned earlier
in the definition for pH it’s a measure of the hydrogen ion concentration of solution. So with plants taking up certain ions, leaving certain other ones behind our pH tends to stabilize slightly down, a little bit more from
the action of those plants so we wind up right about in the middle of that pH 6.5 range or
so, right about there. This will not always
work for all solutions, it really depends on your tap water. Is your tap water, you know pH of eight? It’s not gonna work. Another common problem when
troubleshooting for pH issues is you might have high
carbonate content in your water. It’s very common in our water. What this does is it buffers the pH and it makes it really hard to adjust. So it’s buffering that
pH at a high pH range and even adding this a lot of times won’t change it very much, because there is such
high carbonate content in that solution that it’s
just buffered and stuck right at that high range. If you are over 200
parts-per-million in carbonates and the only way to do that
is to have your water tested to find out for sure what
your carbonate content is, if you are over 200 parts-per-million it is highly recommended that
you get an RO filter system to filter your reservoir
water before putting it in. So, what are some common
mistakes that you see with using pH Up or pH
Down to adjust your pH? As we had said earlier, you do not want to use household products, something that’s going to be varying. You want something that is constant, something that you can rely
on time and time again. Don’t mess around with
other stuff and experiment, you might kill all your plants. Other common mistakes that you will see is adding way, way too much of it, too fast to your reservoir, as I have said in earlier sections, add a small amount, let it
circulate through the reservoir and recheck, come back, you
know sometimes it depends on the size of your system, but you might want to come
back up to half-an-hour later to give it time to fully
disperse into solution ’cause you will see constant variation and you don’t want to
see huge, huge pH swings when you’re adding, it’s
better to adjust it slowly so that the plants do not
get any shock from that. So to avoid making that mistake of overdosing your system with
your pH adjustment solution you want to use a measurement tool always. And always start with a small amount once you have a feel for
how it changes your water and how it changes in relation with your nutrient solution because nutrient solutions are typically a little bit acidic, they will slightly lower your pH as well. Once you have a feel for that you can kind of get into the habit of knowing okay, my 20
gallon reservoir takes, you know a tablespoon to
drop the pH this much. In relation to what your pH is reading, if it’s too high or too low you’re plants may not have the available
nutrients that they need. It may be in solution
but they can’t use it. A pH range of six to 7.5 is recommended, usually mid sixes, are pretty good. In conclusion, pH is extremely
important to plant growth and should be a top priority. So we hope you liked our video. We hope you learned a lot. If you have any questions, if you have any comments, if we left anything out of this video that you would like to know please let us know in the comments below. Again, I am Ethan Walter,
here with Bright Agrotech, until next time. (upbeat instrumental music) Other commons mistakes,
this does look tasty, it is a nice orange drink color. Do not drink it, it probably
won’t be very good for you.