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pH in hydroponics - essentials and master tips · Hydroponics Daily

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  Hello and welcome back to Hydroponics Daily. Today we're talking about pH.
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  It's amiss of me to get over 150 episodes into a podcast about hydroponics and
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  not have talked about pH or certainly not dedicated a whole episode to it.
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  So I'm making up for that now with this episode here.
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  PH, going back to basics, if you missed sort of basic high school chemistry,
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  is the measure of how acid or alkaline a
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  substance is a water-based solution
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  or water so any sort of water-based product or solution it measures how acid
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  or alkaline it is ph actually is about the amount of hydrogen ions pos h plus
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  in the in the water or in the solution and that's why it's got ph The capital H is for hydrogen.
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  Nobody's actually 100% sure what pH stands for.
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  Scientists don't know. Some have said potential hydrogen.
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  I think the French prison de hydrogen or something like this has been muted,
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  but no one's really sure why it came about. But pH is what it is.
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  And if it's pH 1, it's very acidic. And if it's pH 14, it's very alkaline.
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  And so the reason it's important in hydroponics.
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  It's not because when you think of acids and alkaline, you think of them burning
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  your face off, burning your skin off, like sulfuric acid or nitric acid,
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  really dangerous chemicals.
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  And then at the other end, sodium hydroxide, potassium hydroxide.
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  Products that are used in oven cleaner and things like this.
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  So it's not about the actual damage caused to the tissues or anything like that.
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  We're talking about pH is much more in the middle, govern nutrient availability
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  and that's the key thing you have to take away when it comes to pH and plants
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  it's all about nutrient availability if you get to the point where it's scorching
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  the plants because it's too acid or too alkali plant's going to die straight
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  away so it's all about nutrient availability and.
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  So the pH scale is logarithmic, which means that pH 6 is 10 times more acidic
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  than pH 7, and pH 5 is 100 times more acidic than pH 7, pH 4 is 1,000 times.
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  So what might seem like a tiny, tiny change can actually be a massive change
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  in the amount of acidity.
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  So it's called a logarithmic scale, goes up in tens, and so the changes are dramatic.
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  So if you had a nutrient solution that was
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  five to a hundred times more
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  acidic than ph7 now in
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  hydroponics there is a sweet spot and that
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  is 5.5 to 6.5 and
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  in soils you're around the same as
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  well so if you're going in soils you can you can listen to.
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  This episode and get good knowledge from it because the same sort
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  of things occur there are other things that happen in
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  soils that don't happen in hydroponics but we're not going to go into those and so
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  the reason 5.5 to 6.5 is
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  the sweet spots because in that range all of
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  the nutrients that the plant needs are
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  soluble if put into water now if
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  you go outside of that nutrients will start
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  to fall out and depending on what the ph is it will
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  affect that and then some nutrients become extremely locked
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  out and precipitate out when i talk about precipitation it's
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  like the crystallization the falling out of the
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  nutrients and once that happens it's very very difficult if not
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  impossible to get them back into solution even if
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  you change the ph back to the sweet spot so that's
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  why it's crucial in hydroponics so 5.5 to
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  6.5 is the sweet spot you might even hear see people say
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  5.8 to 6.2 is
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  the sweet spot and i don't sort of
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  i don't agree with that because i think they're
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  trying to get too dialed in and the problem is if
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  you do that if you're constantly trying to switch correct your.
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  Ph get it right into that six at 5.8 to
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  6.2 if you're constantly trying to get it into that
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  much smaller sweet spots you're adding
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  ph up you're adding ph down chemicals and you're
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  just increasing the salt levels in the solution
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  and you're wasting a lot of time and a
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  lot of product as well so you can actually harm the
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  plant by messing around with ph too much as
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  long as you're in that 5.5 to 6.5 there will be enough of every
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  single nutrient and if you're seeing issues around nutrients
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  it'll be caused by things other than the ph of that so that's
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  the optimum if you go if you go below 5.5 then
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  certain problems occur some nutrients
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  might become too available and that's not going to be a problem in hydroponics
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  because you they're not being released from the soil so you can get things like
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  aluminium and iron toxicity at very low pH but you're not going to get that
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  in hydroponics because you're not using soil so they're not going to be there to come out of.
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  Out of the soil and into solution. However, you will get lockouts of calcium and magnesium.
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  So that's where you'll start to see calcium deficiencies if your pH is too low.
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  If you're seeing calcium deficiencies and you're in the sweet spot,
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  then that'll just be because of lack of calcium or poor water management,
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  high humidity, things like that.
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  High pH, there you're going to get iron deficiency, manganese deficiency,
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  zinc deficiency, but iron is the main one.
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  All the others will be should occur
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  much later on you'd have to have very high iron levels for
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  manganese or boron or phosphorus to be
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  the first ones that you pick up normally it's going to be iron deficiency so
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  that's intervenal chlorosis on the younger leaves and that's fairly easy to
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  spot so you'll get stunted growth and low growth as well as these iron deficiencies
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  these nutrient symptoms of nutrient deficiencies.
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  How can you manage the pH in hydroponics? The first thing before you start messing
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  around with chemicals is you need to monitor the pH.
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  You can use test strips, so sort of indicator paper that you would use in school.
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  I use these every now and again, they're very easy, but you really want to get
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  a good quality pH pen, not a cheap and nasty one, a really good pH pen.
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  You can get ones that have got integrated EC, electrical conductivity measurements
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  in them and measure it all around your system so if you've got a recirculatory
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  system measure it in the in the gullies as well just to make sure you're not missing anything,
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  monitor at least daily and some systems you
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  can actually set them up so you can get constant monitoring of ph
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  you know we haven't got one at uterine mass it'd
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  be nice to have and then when you if you
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  do try and adjust the ph then adjust gradually don't
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  try to do it all in one go because adjusting water things
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  that are not buffered you know like water fertigation solution
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  if you they will change quickly and very
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  difficult so always use try and dilute the ph up or the ph down first if you
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  if you're struggling and because small changes will make a big difference just
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  a few drops will make a big difference and let your system run through continuously
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  before you add more because you you don't want to have like localized buildups
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  you could add some ph each.
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  And it could get sucked into the system and then not come back again for 10 minutes.
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  So do it really gradually, not in any rush here, especially if you're using
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  silicon products to increase the pH.
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  Then these will take a few hours at least to have their full effect.
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  Silicon is not the main one that's used though. For pH down,
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  it's phosphoric acid, and then pH up, it's potassium hydroxide.
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  So potassium hydroxide, the same chemical that's in oven cleaner,
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  so a hazardous you know chemical and
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  ph down phosphoric acid again dangerous so they're
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  the ones that sold in grow shops you will see in
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  commercial greenhouses especially nft nitric acid
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  being used because they like to add extra nitrogen for
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  tomatoes and cucumbers and things like this which is
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  a good option works effectively and it's adding you know
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  nitrogen nutrition rather than phosphorus nutrition big problem
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  with what nitric acid it does it's a extremely toxic
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  it will you know if you expose your workers
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  to it it and the fumes can be extremely hazardous as well for nitric acid same
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  for hydrochloric acid so nitric acid i've seen kids in the lee valley in essex
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  playing football around ibcs big totes of nitric acid near the greenhouses.
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  And they could have opened one of the valves just messing around and the nitric
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  acid could have spilled out and they could have absolutely just,
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  you know, burned their skin off, burned their bones off, burned their muscle
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  off. You know, it's shocking.
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  You see some sites when you go around commercial hydroponics glass houses,
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  it's supposed to be, you know, state-of-the-art, but that's shocking really.
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  So don't use nitric acid unless you really have to.
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  Never use hydrochloric acid because it's adding chlorine and chlorine is toxic
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  in anything other than minimal levels what else can you use you can use citric
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  acid that's a good organic ph down.
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  That's used in a lot of organic systems just because it's organic doesn't mean it's not,
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  powerful citric acid is very powerful acid we
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  use in a lot of products and it comes in
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  crystalline form or you can buy it in a 50 solution or
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  weaker it does add carbon to
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  the system though and microbes can grow in carbon so
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  if you wanted a completely sterile system you'd either use phosphoric acid
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  or nitric acid if you're a large grower you
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  can get automatic dosing systems that say that can dose in these ph up and ph
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  down if you're using gold leaf or liquid gold it's called in the uk our product
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  then you don't need to worry about ph adjustment because it drags the ph back
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  to the sweet spot every time even if you're adding a really alkaline seaweed extract or a really acid.
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  Growth stimulants something like that if your water's hard or
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  soft it would just drag it back
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  so we one of the great things about gold leaf
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  and liquid gold is that you don't need to bother with pH
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  and also you don't need to bother with these really hazardous chemicals
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  that adjust the pH up and the pH down and a
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  lot of people grow hydroponics at home and if you've
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  got kids running around you don't want the bottles of pH up
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  and pH down especially you know you might misplace them you might mislabel them
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  it's not cool and like that greenhouse with the kids running around the IBC
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  of nitric acid you know you hear some absolute horror stories of kids getting
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  harmed even killed on farms and i would do everything to avoid using nitric acid around kids.
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  Hard tap water with high alkalinity can buffer your system towards a high ph,
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  so um you might want to also consider ro water because you don't your ph will
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  always be rising when you've got that hard alkaline product with lots of carbonate
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  in the in the water so you'll get that drift back towards a high pH.
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  DWC seems to be the one that pH is a real issue with and pH control you can
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  get because of the aeration in NFT and DWC you can get sort of drift back.
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  And a lot of people will either use a lot of pH up or a lot of pH down,
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  depending on their system and how they grow.
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  You tend to only use, find you only end up using one or the other.
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  It depends on the crop as well. Some crops are exuding either hydroxide or hydrogen
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  ions into the water, depending on how they absorb nutrients,
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  especially things like nitrogen.
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  Plants can absorb nitrogen in a number of different ways. and if
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  they absorb it in certain ways they can either push out
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  things that alkali the solution or
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  acidify the solution so um it depends
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  on your crop which one you you find you'll be but you'll find you'll be
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  using one more than the other over time
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  some interesting some interesting quirks about
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  ph if you're growing hydrangeas and you
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  have a high ph the flowers turn pink and
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  if you have a low pH of the growing solution or
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  the soil then the flowers go bright blue and that's
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  because the anthocyanin pigments in the petals attach
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  to aluminium ions below pH 5.5
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  and that changes the pigment to blue so depending
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  on which one you like you could adjust the pH so I like red
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  ones but a lot of people like blue ones so yeah have
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  you ever seen those certain certainly certain types it's
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  um the mop head hydrangea hydrangea
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  macrophylla and mountain hydrangeas hydrangea serrata
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  but they grow a lot in in the wirral near
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  liverpool and you often see the bright blue hydrangeas there
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  and that's because the aluminium attaching to the ph in
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  those acidic soils so interesting fact that's
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  going to be of no use to anyone apart from hydrangea growers also if
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  you're using elemental sulfur burning elemental
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  sulfur in your grow greenhouse or your grow room be careful because that rains.
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  Down sulfuric acid on your plants so you will see us by a drop in ph dramatically.
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  If you're using sulfur to control pests and disease people think of it as this.
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  Organic natural product even if you're putting powder sulfur on your growing media.
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  It'll break down to sulfuric acid by the microbes in
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  this in the growing media so always be careful using any
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  elemental sulfur whether you're burning it or spraying it
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  or using it and mixing it into the
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  grow media always be careful because that is going to drop your ph dramatically
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  and it's not good for your health either if you're using
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  poor quality mineral wool that can raise the ph up probably due to limestone
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  in the material that's being used so always soak and rinse rock wool before
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  planting if you are if you if
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  you do get precipitation of nutrients out because the ph is not optimised,
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  these can clog up the roots, around the roots, or more dangerously, they can block.
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  Filters and drippers and
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  if that happens then you can get a buildup of
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  pressure or worst case scenario your system doesn't
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  drain back into the tank and you can get a flood so you
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  need to be careful and that normally happens at high ph
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  but you can also have a lower ph as well so just
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  keep an eye on that you can get the release of
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  so we say toxic elements as well so like aluminium but also
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  heavy metals so if you've got really extreme ph
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  even if you're like using so don't use like things like bleach
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  to clean any material unless you
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  know it's absolutely safe for you can
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  use alkaline material on that and you clean your system out
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  you may be growing a plant that likes acidic conditions
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  in which case you might lower the ph just below 5.5 but
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  still not below 4.5 these plants
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  are called ericaceous because they most of
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  them belong to the ericaceae family the
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  erica the heather family so things like rhododendrons azaleas there
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  are other plants in other families that are also classed as ericaceous and
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  the technique so that's what gardeners call them ericaceous the actual technical
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  term for them is calcifuges or refugees from calcium the way i remember it so
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  calcium is we think of as being high ph so calcifuges and then plants that like
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  calcium and high pH are calcium coals.
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  Calcium coals are things like brassicas and many meadow orchids.
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  You've got your calcium fuges that like acidic conditions and your calcium coals.
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  If you know your plant's one of these, then you might go on the upper end or
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  the lower end of the sweet spot that's normally used for hydroponics.
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  The vast majority of plants are not calcium coals and calcium fuges.
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  As I said, the plants, the way they absorb different forms of nitrogen can affect
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  the pH of the fertigation solution, and that's why it's always good to have
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  the correct balance of different forms of nitrogen in the base fertilisers.
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  A lot of hydroponic fertilisers that are new often fail in this,
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  and they can cause dramatic shifts in pH.
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  So if you look at gold leaf, or as it's called in the UK, liquid gold, there's
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  a good balance of nitrate and ammonia
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  forms of nitrogen so that they are absorbed in
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  the right balance and so that the nitrogen doesn't dramatically
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  change the pH so another reason to use
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  that product if you're new to hydroponics or
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  you want to produce a really clean good high yield and
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  grow definitely recommend Goldleaf if you're in the US and then
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  Liquid Gold which we've launched this year in the UK if you're
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  outside of those countries then give us a shout I'm sure
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  we could find a way to get that product to you and we're always
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  looking for distributors outside of the US and the
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  uk we do sell the product into australia under
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  a different brand name if you want to know what that brand name is just give us a contact and
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  we can let you know that's been hydroponics daily for today all
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  about ph if you think i've got anything wrong let me know and
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  probably not the last time we'll revisit ph
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  because it's so important in hydroponics it's one of those things you really
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  need to get dialed in it's really easy to do that it's very easy to monitor
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  ph pens are really affordable and once you get it going you should be producing
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  really good crops so until tomorrow that's been hydroponics daily thank you very much for listening.