PH A Basic explanation

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Glassdub

Glassdub

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So you may and may not depending on the makeup... like I say in my original post PH is not really something you can use on its own.

You can look up your water report or post it here and I can give you the low down on it.

But to answer typically the ratio of calcium to Mg is not adequate in tap water... most times you will find adequate calcium but very much lacking magnesium and as we know the nutrient ratios are extremely important to maintain. So in this case instead of adding cal mag you only need to add Mg to bring the ratio back. Ideally about 100ppm Cal and 50ppm of Mg. In most cases if you ppm from tap is between 100-200ppm simply adding 1 gram per gal of magnesium sulfate (epsom salt) will bring the ratios back into a favorable place.
The PPM checked right now is 128.
 
KingHale

KingHale

61
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I’m not sure why I’m just now seeing this, but I test my water after I add nutrients. I don’t have an accurate means of measuring what comes out, as I tend to add just enough water to create a drip but never really accumulates into a puddle.
My tester stays in the soil permanently. I check it every few hours. In all honesty, I’m not completely reliant on the meters readings, but they do encourage me. I have fingers that sense moisture and a nose for excessive moisture. I know that my active and passive air flow is working. Primarily, the plant looks good and I try to just let it do it’s thing.
I will say this: my first two grows were in 100% Fox farm happy frog with no mix, no perlite, no crushed dolomitic limestone, nothing. That may have been why the meter read what it did.

On my most recent attempt, I am copy-catting the idea of mixing 40% happy frog, 40% ocean forest and 20% perlite. I’m also going full blown Fox farm nutrient schedule.
I always pH check my soil prior to watering. Basically, I flip the switch to pH, wiggle the meter and begin getting water ready. By the time I’ve got my water ready, I know the relative oH of the soil. Usually high, just around 7. I collect rainwater, and I add the Fox farms full nutrient schedule as recommended to the T, then pH balanced the water using no more than 2 drops of pH down and no more than 25 drops of pH up after that to a pH balance which always falls right around 5.9 - 6.3. I use a BlueLabs pH meter that i calibrate monthly.
I then put that water into my sprayer and administer the water. When I’m done, ill
Switch the meter back to moisture, wiggle it, and check in 19 minutes. Its usually above 6, which is good. It will eventually create a drip, but won’t create a puddle if I’ve done it correctly. Then I switch the meter back to pH, and check it later. I’ll admit, I’m less diligent in checking the pH after 10 minutes, but even after an hour, the meter is on a solid 6, so whatever I’m doing seems to working. I’m always trying to improve.
If you need pH down after adding Fox Farm nutrients, something is probably wrong.
The only time I ever use pH down is when I’m preparing rainwater without nutrients.
 
Aqua Man

Aqua Man

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Its about 20ppm coming out of RO (That 20ppm is from the alkaline stage (The 5th-9th stages are our Alkaline Filter adding 5 stages of mineralization, antioxidants, and oxygen to your water. )
800ppm when tested after running through entire system
and oddly enough its 800ppm when tested directly from town (outdoor faucet). Its very easy for me to tap into a direct town water line as well if some of that water would be beneficial.

So, what do you think would be my safest path forward to experiment with in my new living soil run? Straight RO water, then add cal/mag or epson salt as plant show deficiency? I think you are correct and it makes total sense about salt being the primary TDS in my (non-RO) water, not cal/mag.
Yeah RO and then add cal mag to reach 150ppm including the 20ppm after and your solid
 
Aqua Man

Aqua Man

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SSgrower

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I've collected "rain water" which Ph'd to 7.9 and my buddy growing near me says he never ph's or anything, old school guy 30 + years growing. I am more science oriented and trained for a Master Gardener's certificate thru Texas A&M.
 
Frankster

Frankster

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I've collected "rain water" which Ph'd to 7.9 and my buddy growing near me says he never ph's or anything, old school guy 30 + years growing. I am more science oriented and trained for a Master Gardener's certificate thru Texas A&M.
rain water could ph out high like that but it will acidify almost instantly on contact with virtually anything, because the elevated ph in the rain water has exceptionally low concentrations. it's just a high ph substance that's causing that curiosity, probably potassium hydroxide or something similar, that's become soluble in the water for some reason.

My water is high coming out of RO, well above 7 but I use it straight most of the time, with no problems. The buffer in your medium should counter those traces. But certainly at 7.9 it should be monitored, or dialed in somehow.
 
Last edited:
MIAquaFire

MIAquaFire

49
18
OK I'm going to do my best to explain PH since its something that is for the most part greatly misunderstood and can be confusing to new growers and even experienced growers alike. This will explain why we need both ppm and PH meters to give us informed information about PH

This will be a simple guide leaving out a lot of information. So lets get started with a couple of definitions to help you understand.

What is PH?​


PH is a measurement of how alkaline or acid a solution is based on measuring hydrogen ions. It tells us nothing more than the ratio of acidic to alkaline elements. It does not tell us how much of each the solution contains or the alkalinity of the water.

What is alkalinity?​


Alkalinity is the measurement of the waters buffering capacity (ability to neutralize acids). Its the total amount of carbonate and bicarbonate in the water that affects its ability to resist change to PH. If you know the alkalinity you can actually calculate the amount of acid of varying types needed to reach your target PH but we wont get into that.


So now we have a basic understanding of the difference lets get into some examples of source water and how alkalinity will affect PH.

RO and Distilled water​


Ro and Distilled water is very low in mineral content containing carbonate or bicarbonate sources, we know this because if we test the ppm its usually under 40 and as low as 0ppm. This means it has a very low alkalinity (ability to neutralize acids) and is easily influenced by anything added that's acidic. But likewise it does not contain acid and is easily influenced by anything added that's basic. This results in a very unstable PH that can be easily influenced by anything added or anything its added to. In hydro the ideal ppm of carbonate/bicarbonate sources to provide an adequate buffer will be 50-100ppm with 75ppm being the target. Less than this and PH may swing to fast and be unstable, more and it will not drift enough and will require too much acid that could affect nutrient ratio's negatively depending on the acid used. By adding alkalinity and then acid we provide a more stable PH because adding more of either will have less impact on the overall ratio of acidic to basic elements

When used in hydro it should have alkalinity (a buffer) added back to prevent wild PH swings. Any source of carbonates, bicarbonates, silicates or hydroxides will work to create alkalinity. Sources i would recommend would be calcium carbonate, potassium bicarbonate (commonly sold as PH up) and finally what i would consider the best option is potassium silicate as it is a source of potassium and silica which are both excellent for cannabis. When using RO or distilled you will want to add back some calcium and magnesium if your nutrients are not designed for RO/distilled water as that's usually what Ro filters are removing for the majority. But most cal/mag is in the form of nitrate and provides no alkalinity (buffering capacity) so adding one of the previously mentioned or other is still a must.

When used in soil this unstable PH is actually IMO beneficial if you have a pre buffered soil (which you should) This means the water will have no impact on the PH potential (more on this later) of the soil and will almost instantly be influenced by the soil to the take on the PH of the soil makeup. This is why i feel we do not need to be PHing our nutrient solution for soil grows (unlike soiless and hydro). The soil is what will adjust the PH of our nutrient solution.

Tap Water​


OK we all know tap water varies a lot form place to place and I will explain the basics of how to determine if your tap water is suitable or not for use. First we want the PPM and second we want the makeup of that ppm if available. Generally speaking the majority of the PPM makeup will be calcium carbonate. This is used to buffer the water supply and prevent acidic conditions that erode the coatings and will break down piping and leach them into the water supply such a lead (Flint Michigan ring a bell?) So we can generally assume the majority of the PPM in tap water is likely calcium carbonate but also some others like magnesium, sulfur, phospahte, iron etc. So if you have a ppm of 100-200ppm you can assume roughly 50-75% of that is calcium carbonate. Remember our target is 75ppm carbonate/bicarbonate sources to provide an ideal alkalinity (hope we are starting to see how import alkalinity is and we can't just go by PH) Now there are some cases when some sodium may be used such as sodium bicarbonate aka baking soda (can also be used as a buffer in a pinch but not recommended as a long term option) so we can google our local water report and see the makeup of the ppm in the water.

Soil PH potential​


Now when we buy a prebufferd soil like most of the ones we use they come "Prebuffered" (alkalinity adjusted) what does this mean? This means the company has added amendments that when water is added the resulting PH of the water in the soil will be in a favorable range for growing our plants. Often times peat is used to lower PH and lime is used to raise PH in these soils. Just like in water we want to control the alkalinity (buffering capacity) of the soil to have a stable PH that is not easily influenced by adding things such as nutrients or other. Unlike hydro and soiless where we control the alkalinity (buffering capacity) of the water by adding it directly to the water it is applied to the soil. Which brings me back to my point of we don't need to PH our nutrient solution in soil because the soil provides the buffering and will adjust the PH. Now things like lime and peat break down slowly over time and only soluble elements will impact PH so this is how they control the PH in soil over long periods of time, because it breaks down slowly and only a small amount is soluble at a time its unlikely after a grow it has been depleted. But if we are reusing the soil we should be looking at re amending the buffering capacity before using again to ensure there is enough to last through the next grow. Often times farmers will do this once a year before seeding crops.

Effects of nutrients and source water on PH​


First the PH down acids we use tend to break down much faster than the alkaline sources we use in both hydro and soil. For this reason we see a hydro systems PH generally rise over time unless something is creating more acid like decaying roots in which case we may actually see PH going down. Typically a PH increase of 0.2 in a 24 hr period is desirable and by adjusting the alkalinity we can control the PH drift. In the case of soil the acids used to bring PH down before feeding break down quickly and the alkaline and acidic buffer we have created minimizes the impact so they are really of not much benefit and have virtually no impact on long term PH potential of the soil. This is why we can't use them to lower high soil PH once we have an alkaline source buildup. However in hydro and coco PHing the nutrient solution is important because unlike soil there is not an adequate buffer established although in coco it is possible to do so.

Generally speaking the ratio's of nutrients we use will be acidic so when we get a buildup of nutrients we will almost always see PH drop. This is where you often hear ppl say flush the media. What this does is dilutes the dissolved elements and will remove some from the media in runoff.

Conversely a water source with high alkalinity can build up in the media and cause the PH potential of the soil to rise over time and in turn the PH of the water added to it. This is the reason we should look at the alkalinity of the water source not the PH as PH cannot measure the potential influence but rather only result.

Often in both circumstances its a good idea to flush the media to remove excess amount of available elements that may be affecting the PH negatively.

I'm gonna stop there and if anyone has questions i will do my best to answer them. If you have something you would like to add please do.


Aqua Man
What do u think about this water report?
 
Screenshot 20211208 215851 Drive
Glassdub

Glassdub

966
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Acid Rain pH at 4 some of my AC run off water was lower than that so... that be corrosive. 😁
 
Frankster

Frankster

Never trust a doctor who's plants have died.
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What do u think about this water report?
Horrible; ie. cannabis worst nightmare scenario .☠️👾☠️ You must live in a dry desert somewhere.

I would be most concerned about those chloride and floride levels, possibly even barium. The ppb are pretty tiny, so not too much worry on As or Lead; but neither is beneficial on any level. The hardness is off the chart; basically that water should be filtered or at minimum; allowed to sit in a 5 gal bucket for 24-48 hours, and dip it out without disturbing the resulting bottom sediment. take the top 2/3 or 3/4 and discard, rinse and repeat.


Personally; I wouldn't consume that shit myself, let alone feed it too the plants.
But filtering it would be a far more prudent choice; IMO; even if it's just run though an inexpensive garden hose filter.. Or a stack of wood charcoal put in some sort of tube, then out the other side.
 
Last edited:
4.19

4.19

32
18
OK I'm going to do my best to explain PH since its something that is for the most part greatly misunderstood and can be confusing to new growers and even experienced growers alike. This will explain why we need both ppm and PH meters to give us informed information about PH

This will be a simple guide leaving out a lot of information. So lets get started with a couple of definitions to help you understand.

What is PH?​


PH is a measurement of how alkaline or acid a solution is based on measuring hydrogen ions. It tells us nothing more than the ratio of acidic to alkaline elements. It does not tell us how much of each the solution contains or the alkalinity of the water.

What is alkalinity?​


Alkalinity is the measurement of the waters buffering capacity (ability to neutralize acids). Its the total amount of carbonate and bicarbonate in the water that affects its ability to resist change to PH. If you know the alkalinity you can actually calculate the amount of acid of varying types needed to reach your target PH but we wont get into that.


So now we have a basic understanding of the difference lets get into some examples of source water and how alkalinity will affect PH.

RO and Distilled water​


Ro and Distilled water is very low in mineral content containing carbonate or bicarbonate sources, we know this because if we test the ppm its usually under 40 and as low as 0ppm. This means it has a very low alkalinity (ability to neutralize acids) and is easily influenced by anything added that's acidic. But likewise it does not contain acid and is easily influenced by anything added that's basic. This results in a very unstable PH that can be easily influenced by anything added or anything its added to. In hydro the ideal ppm of carbonate/bicarbonate sources to provide an adequate buffer will be 50-100ppm with 75ppm being the target. Less than this and PH may swing to fast and be unstable, more and it will not drift enough and will require too much acid that could affect nutrient ratio's negatively depending on the acid used. By adding alkalinity and then acid we provide a more stable PH because adding more of either will have less impact on the overall ratio of acidic to basic elements

When used in hydro it should have alkalinity (a buffer) added back to prevent wild PH swings. Any source of carbonates, bicarbonates, silicates or hydroxides will work to create alkalinity. Sources i would recommend would be calcium carbonate, potassium bicarbonate (commonly sold as PH up) and finally what i would consider the best option is potassium silicate as it is a source of potassium and silica which are both excellent for cannabis. When using RO or distilled you will want to add back some calcium and magnesium if your nutrients are not designed for RO/distilled water as that's usually what Ro filters are removing for the majority. But most cal/mag is in the form of nitrate and provides no alkalinity (buffering capacity) so adding one of the previously mentioned or other is still a must.

When used in soil this unstable PH is actually IMO beneficial if you have a pre buffered soil (which you should) This means the water will have no impact on the PH potential (more on this later) of the soil and will almost instantly be influenced by the soil to the take on the PH of the soil makeup. This is why i feel we do not need to be PHing our nutrient solution for soil grows (unlike soiless and hydro). The soil is what will adjust the PH of our nutrient solution.

Tap Water​


OK we all know tap water varies a lot form place to place and I will explain the basics of how to determine if your tap water is suitable or not for use. First we want the PPM and second we want the makeup of that ppm if available. Generally speaking the majority of the PPM makeup will be calcium carbonate. This is used to buffer the water supply and prevent acidic conditions that erode the coatings and will break down piping and leach them into the water supply such a lead (Flint Michigan ring a bell?) So we can generally assume the majority of the PPM in tap water is likely calcium carbonate but also some others like magnesium, sulfur, phospahte, iron etc. So if you have a ppm of 100-200ppm you can assume roughly 50-75% of that is calcium carbonate. Remember our target is 75ppm carbonate/bicarbonate sources to provide an ideal alkalinity (hope we are starting to see how import alkalinity is and we can't just go by PH) Now there are some cases when some sodium may be used such as sodium bicarbonate aka baking soda (can also be used as a buffer in a pinch but not recommended as a long term option) so we can google our local water report and see the makeup of the ppm in the water.

Soil PH potential​


Now when we buy a prebufferd soil like most of the ones we use they come "Prebuffered" (alkalinity adjusted) what does this mean? This means the company has added amendments that when water is added the resulting PH of the water in the soil will be in a favorable range for growing our plants. Often times peat is used to lower PH and lime is used to raise PH in these soils. Just like in water we want to control the alkalinity (buffering capacity) of the soil to have a stable PH that is not easily influenced by adding things such as nutrients or other. Unlike hydro and soiless where we control the alkalinity (buffering capacity) of the water by adding it directly to the water it is applied to the soil. Which brings me back to my point of we don't need to PH our nutrient solution in soil because the soil provides the buffering and will adjust the PH. Now things like lime and peat break down slowly over time and only soluble elements will impact PH so this is how they control the PH in soil over long periods of time, because it breaks down slowly and only a small amount is soluble at a time its unlikely after a grow it has been depleted. But if we are reusing the soil we should be looking at re amending the buffering capacity before using again to ensure there is enough to last through the next grow. Often times farmers will do this once a year before seeding crops.

Effects of nutrients and source water on PH​


First the PH down acids we use tend to break down much faster than the alkaline sources we use in both hydro and soil. For this reason we see a hydro systems PH generally rise over time unless something is creating more acid like decaying roots in which case we may actually see PH going down. Typically a PH increase of 0.2 in a 24 hr period is desirable and by adjusting the alkalinity we can control the PH drift. In the case of soil the acids used to bring PH down before feeding break down quickly and the alkaline and acidic buffer we have created minimizes the impact so they are really of not much benefit and have virtually no impact on long term PH potential of the soil. This is why we can't use them to lower high soil PH once we have an alkaline source buildup. However in hydro and coco PHing the nutrient solution is important because unlike soil there is not an adequate buffer established although in coco it is possible to do so.

Generally speaking the ratio's of nutrients we use will be acidic so when we get a buildup of nutrients we will almost always see PH drop. This is where you often hear ppl say flush the media. What this does is dilutes the dissolved elements and will remove some from the media in runoff.

Conversely a water source with high alkalinity can build up in the media and cause the PH potential of the soil to rise over time and in turn the PH of the water added to it. This is the reason we should look at the alkalinity of the water source not the PH as PH cannot measure the potential influence but rather only result.

Often in both circumstances its a good idea to flush the media to remove excess amount of available elements that may be affecting the PH negatively.

I'm gonna stop there and if anyone has questions i will do my best to answer them. If you have something you would like to add please do.


Aqua Man
@Aqua Man - This is one area I have been a little perplexed by. My situation:

Im growing in Fox Farm Ocean Forest
I use tap water through a chlorine filter
My "out of hose" ph runs between 7.8 and 8.2
I PH down to get between 6.4 and 6.2

My take away is that since I'm growing in soil Im wasting my time, and money on ph down. Am I getting this right?
 
MIAquaFire

MIAquaFire

49
18
Horrible; ie. cannabis worst nightmare scenario .☠️👾☠️ You must live in a dry desert somewhere.

I would be most concerned about those chloride and floride levels, possibly even barium. The ppb are pretty tiny, so not too much worry on As or Lead; but neither is beneficial on any level. The hardness is off the chart; basically that water should be filtered or at minimum; allowed to sit in a 5 gal bucket for 24-48 hours, and dip it out without disturbing the resulting bottom sediment. take the top 2/3 or 3/4 and discard, rinse and repeat.


Personally; I wouldn't consume that shit myself, let alone feed it too the plants.
But filtering it would be a far more prudent choice; IMO; even if it's just run though an inexpensive garden hose filter.. Or a stack of wood charcoal put in some sort of tube, then out the other side.
Believe it or not im in michigan lol. I already run a ro for my home drinking water and I also run a hydrologic evo 1200gpd for my garden! I was just curious what others thought of the report because it kows my mind the townshio says its ok to drink. Ironically there has been about 9 people in my nieborhood (all around the same age) with the same type of cancer over the last 5 years..... also all of whom have drank this tap water for over 25 years now
 
Frankster

Frankster

Never trust a doctor who's plants have died.
Supporter
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@Aqua Man - This is one area I have been a little perplexed by. My situation:

Im growing in Fox Farm Ocean Forest
I use tap water through a chlorine filter
My "out of hose" ph runs between 7.8 and 8.2
I PH down to get between 6.4 and 6.2

My take away is that since I'm growing in soil Im wasting my time, and money on ph down. Am I getting this right?
Yea aqua hasn't been on for awhile, but you are 100% correct. Ph out of the tap is basically irrelevant if the ppm is below say 50 ppm, or lower. concentrations is what you need to buffer, the pH of tap/rain water self adjust once it hits a buffered substrate.

pH adjustment becomes critical when salts, or fertilizers have been added. Especially critical, and less responsive at higher ppm range. That's where buffering; tethering; tying a strong base to weak acids become very useful. Most of the elements that we want to give the plant end up on the acidic end of the scale, for the most part.

Keep in mind; foxfarrm forest isn't enough in and of itself to carry you though the entire grow. It will get you started into the first few weeks at most; (sprouting) then your plants are asking for something more. If you not giving them something more; your holding them back.

I would say week 3->4 max. If your offering organics, there's cook time that they need to be nitrified, so even earlier; perhaps.
 
Last edited:
T

TryingToGrow

Supporter
290
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I have to pH my tap water to ~5.7 pH to be able to grow in any medium (organic soil, non organic soil, organic backyard soil, coco, anything else I have tried), to keep the pH of the medium 5.8-5.9 ish.

Out of the tap it's 7.7 pH, 300ppm. If I don't keep the pH of the medium around 5.8-5.9, my plants won't grow very well or at all. I like to make it a little lower because everything's pH always seems to be rising. Except peat, which I don't use anymore and only ~used by mistake, that stuff's pH likes to go down for me.
 
Last edited:
Glassdub

Glassdub

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IMHO, It's better to not acid down water at all as in the end the medium will acid down from feed & its more of a struggle to keep it up than down.
 
tobh

tobh

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IMHO, It's better to not acid down water at all as in the end the medium will acid down from feed & its more of a struggle to keep it up than down.
Depends on the media. pH is a tricky thing for a lot of growers, new and seasoned. In soil, pH of input solution is a damn near irrelevant if the soil is built properly. In hydro, you gotta have adequate alkalinity or keeping the solution from swinging like crazy is going to drive you insane.

If pH is diving in hydro, you've bad bacterial cultures blooming. It's a symptom of a deeper problem. pH should be pretty damn stable, on move on a smooth curve as EC and water levels change.
What about di water. Is this an option?
Distilled water could be used, but it's inadvisable since it's zero PPM. Even RO is pretty low but it still tends to have some EC in it, even if it's not terribly significant. You'll just have to use more alkaline buffering and distilled water just isn't economical for long term use.
 

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