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The limitations of EC meters: what they can, and can't, tell you · Hydroponics Daily

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  Hello and welcome back to Hydroponics Daily, your go-to podcast for everything soilless cultivation.
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  I'm your host, Dr. Russell Sharp. I'm the founder of Utrema Limited.
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  We make interesting fertilisers, novel biostimulants and organic biopesticides,
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  including gold leaf, or as it's called in the UK, liquid gold.
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  And that's important because we're going to be talking about EC meters today,
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  and I'm going to be mentioning gold leaf a few times on this
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  podcast about ec meters now if you listen to
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  the first 100 episodes of this podcast you'll know i'm a big fan of ec meters
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  they're an invaluable tool to help you estimate the amount of fertilizer in
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  a solution of water and but really the reason i really love them is that when
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  you have something like cocoa and you've been feeding it.
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  When you, you should always run off a small amount of solution out the bottom
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  of the sources if you're growing in cocoa or peat or soil and about 10 to 20%.
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  And if you put an ECP pen in that outflow, that runoff, it tells you how much
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  buildup of fertilizer there's been in the grow media.
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  And if it's too high, then you need to flush more solution through.
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  A lot of people don't flush out runoff and it's very important.
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  You do need to have some way of getting rid of that runoff as well.
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  Otherwise it will build up and you won't get as good a crop nowhere
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  near as good a crop and even houseplants as well that's
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  the problem with houseplants is you feed them for years and years and years and this
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  salt level builds up you stick an ec pen in there and you go oh my god what
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  have i done and then you flush them all out and you'll find two weeks later
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  all your houseplants are growing away really well ec pens are great however
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  today we're going to talk about the limitations of EC pens, EC meters,
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  whether they're handheld devices or in-line, computer controlled.
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  So the first one is EC shows overall iron concentration, so the charged elements,
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  all the dissolved salts combined.
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  It does not identify only nutrients, so it's not just your nutrients,
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  and it can't differentiate between any of the nutrients.
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  So it could be really high in potassium or really high in
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  magnesium or really high in sodium you don't know it
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  could be a nutrient that's high in one particular could be a blend they
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  could all be in the right ratios or it could be a toxin
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  like sodium so it could be from unwanted salts
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  or unbalanced salts and you would never know so we
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  can't distinguish between them sodium chloride even
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  arsenic things like this would all be picked up on an ec pen the other thing
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  is that ec ec measurements are temperature dependent and conductivity changes
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  with temperature so the meter if the meter lacks automatic temperature compensation
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  in the readings can be inaccurate,
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  As I said, there's no information about nutrient ratios. So if your plants have
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  absorbed loads of calcium or loads of nitrogen and you're adding fertilizer
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  in and you think, oh, I've rebalanced it to that, the stated EC value,
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  then you still might be deficient in one of the nutrients. You can't tell that.
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  Another limitation is they don't have to set pH and pH affects nutrient availability.
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  So EC only measures the salt concentration, not the acidity or alkalinity.
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  So you need an extra pen to do that and here
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  is a big one organic fertilizers often don't
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  show up well many organic nutrients are ionic.
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  Until broken down by aren't sorry
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  aren't ionic until they're broken down by microbes so they
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  might be amino acids or proteins or
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  peptides and until broken down they won't
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  be picked up there could be a whole host of other
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  different compounds containing the nutrients so water may
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  test low for ec but still be
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  nutrient rich and so if you then this
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  is the big problem is that people get ec charts and they say oh
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  i've heard that for this crop c then
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  i need this ec value
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  2000 you know for example and that's
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  just not true the only time you should refer to ec
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  charts blindly is when you're
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  using a bog standard fertilizer that is one of
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  the a and b fertilizers and it uses the
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  same recipe as the the bog
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  standard hydroponic feeds if you're using anything interesting
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  like an organic fertilizer do not use
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  an ec chart and if you're using gold leaf or it's called in the uk liquid
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  gold don't use an ec chart because you will massively over fertilize your crops
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  and over fertilizing is worse than under fertilizing so don't just go off that
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  ac value what you can do is add the fertilizer to your water in the ratios recommended.
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  By the manufacturer then take an ec measurement and then use that measurement
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  as your guide don't use the charts off the internet don't use what your mate barry tells you.
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  Use the ec value in your water when you put the fertilizer into the recommended value okay,
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  so that's really important so organic fertilizer
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  anything novel a fertilizer that's not run
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  of the mil that that's one of the big limitations don't
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  just then add them to the level that's stated
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  on all these bog standard charts nutrient uptake
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  changes ec unpredictably unpredictably so
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  plants remove specific ions while leaving others behind
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  and ec mean look safe when nutrient balance is great i think we've already covered
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  that so it's what are ec good ec meat is good for they're good for tracking
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  relative fertilizer strength over time so once you've got that baseline level
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  You can then use that as your reference point and try and always maintain that.
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  It helps you avoid salt buildups in hydroponics and in semi-hydroponics,
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  and it's fast and inexpensive monitoring.
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  I always say my why i
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  don't always say that's a lie i do always
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  say it but i didn't come up with it the person who came up with this from my
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  eyes is professor bill davis at lancaster university shout
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  out to bill he always used to say to me change as
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  little as possible in a plant science
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  experiment and measure as much as possible and
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  if you ec is one of these things
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  that you can measure along with pH and monitor it all the
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  time and you'll never think oh no I didn't monitor
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  enough and the other thing you'll never say is oh I didn't take
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  enough pictures of my experiment or my crop they're things things that plant
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  scientists never say they don't never say oh I collected too much data or too
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  many I measured too many variables I didn't take I took far too many photos
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  of my experiment you'll always come to regret not doing enough of those two
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  things What you will say is,
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  oh, I made my experiment far too complicated, I changed far too many variables,
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  and then that made the amount of data points I had to collect so much more,
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  and my data was useless because I changed so many variables.
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  So change as little as possible, measure as much as possible,
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  and take as many pictures as possible.
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  Okay, so in summary, EC meters are great, but they do have their limitations and do not use the.
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  The measurements on charts unless you're using a bog
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  standard hydroponic fertilizer and not doing anything different
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  from the norm if you use an organic or an interesting
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  fertilizer like liquid gold or gold leaf gold
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  leaf in the us or liquid gold in the
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  uk then always use your
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  reference point add it to the your your particular
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  tap water or ro water measure it and
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  then use that as your baseline to work towards hope that's
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  been useful and not too complicated for today i was
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  going to do an episode on how ec meters work but i
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  think it's quite self-explanatory they
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  measure the electrical conductivity the the the
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  flow of electrons through water medium and
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  obviously when you've got more ions that's easier more they
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  can move faster all right thank you very much for listening until
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  tomorrow that's been hydroponics daily if you found it useful at all
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  a review because it's worthless it doesn't help us move up
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  the charts but if you could check out utrema.co.uk that would help me spread
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  the word about what we're doing at utrema helping reduce the amount of toxins
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  that are entering the food system and our soils and our growing systems if you
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  struggle to spell utrema it's latin for wasabi all right thank you very much
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  for listening until next time goodbye.