Ph Dropping From 5.8 To 3.9 Overnight! What Is Causing This?

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jumpincactus

jumpincactus

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The potential hydrogen, or pH, of a nutrient solution or soil plays a vital role in horticulture. In fact, the pH directly influences whether or not essential elements will be available for uptake by plants.

Before explaining how that works, let’s first look a little closer at pH. On the pH scale, seven is considered neutral. All readings above seven are considered alkaline, and all readings below seven are considered acidic.

The pH scale is an exponential logarithmic scale. In other words, every number on the pH scale represents an increase or decrease of tenfold. For example, a pH value of four is ten times more acidic than a pH value of five and 100 times more acidic than a pH value of six.

The same holds true for readings above seven. For example, a pH value of 10 is 10 times more alkaline than a pH value of nine and 100 times more alkaline than a pH value of eight.

In horticulture, the pH level of a nutrient solution or soil is important because every essential element used by plants has a pH range in which it can be absorbed. If the pH fluctuates too far from that range, a nutrient lockout may occur and cause nutrient deficiencies, hindering the growth and yield of a garden. For most hydroponic gardens, the ideal pH range is between 5.5-5.9. For most soil gardens, the ideal pH range is between 6.3-6.8.

So, what exactly determines the pH of a nutrient solution? The pH of a nutrient solution is influenced by four main factors: the water source, the nutrients, microorganisms (bacteria), and growing medium. It will help a horticulturist greatly if they have a basic understanding of each.


Water Source
When I am asked about the pH of a nutrient solution, I always respond, “consider the source.” The source of the water a grower uses is the number one contributing factor to the nutrient solution’s initial pH and its pH stability over time.

Tap water is probably the worst choice a grower can make in terms of pH stability as it’s full of elements and chemicals that will affect the overall pH of the final solution. Calcium and magnesium are just two of the elements usually found in non-ideal ratios in tap water, contributing to pH fluctuations.

Growers with hard water experience continual problems with pH fluctuations thanks to high concentrations of calcium and magnesium. To remove excess or unwanted elements or chemicals, many hydroponic growers choose to use filtration devices, such as reverse osmosis systems. When done correctly, reverse osmosis will provide a horticulturist with pure water that has a neutral (seven) pH.

Depending on the water’s surrounding environment, the pH can also change over time. For example, when water with a neutral pH is exposed to air, the pH will slowly become more acidic as the water absorbs carbon dioxide from the surrounding air. For most growers, this pH fluctuation is minimal and doesn’t require any further attention.

However, growers who enrich their gardens with high levels of CO2 may experience more dramatic decreases in the system’s pH. The best way to minimize this problem is to remove the reservoir or holding tank from the room that is enriched with CO2.

This way the water in the reservoir is no longer exposed to the high concentrations of CO2. This is also why hydroponic systems where the nutrition solution makes minimal contact with the CO2-enriched growing environment are far less affected by phenomenon.


Nutrients
After securing a relatively balanced water source, growers should examine their nutrients and what effect they make on the solution’s overall pH. One thing to remember is the more nutrients that are added, the more the pH will be impacted.

In other words, if a gardener plans on using a 24-part nutrition regimen, they should plan on taking a lot of time to figure out and balance the solution’s pH.

Once you know how a nutrient affects pH, you can adjust the solution to bring it back to neutral. All adjustments should be made five to 10 minutes after all the nutrients have been added to the water. This will give the solution’s pH some time to stabilize.

Even after making pH adjustments to the solution, however, it’s possible the overall pH will fluctuate over time. As the nutrients break down, some chemical compounds are absorbed by the plant and some are left in the solution.

It’s these unused acidic and alkaline compounds that can cause pH fluctuations. The plants themselves can also affect the solution’s overall pH. As they absorb nutrient ions, they give off ions in return. For example, when a plant absorbs potassium ions, it gives off hydrogen ions that lower the pH.

When a plant absorbs nitrogen ions, it gives off hydroxyl ions that result in a rise of pH. In other words, every chemical reaction happening in a plant’s root mass can potentially affect the pH of the nutrient solution.

Microorganisms (Bacteria)
The countless microorganisms found in the growing medium, reservoir, nutrient solution, and root mass can also affect pH. In most cases, there is no negative effect when these microorganisms are in check. However, certain colonies of bacteria can be the cause of constant downward (more acidic) fluctuations in the solution’s pH.

A good indicator that a bacteria colony is affecting the pH is when the solution’s pH becomes acidic quickly—within a few hours—after initial adjustments have been made. This is especially true if the solution continues to go acidic even after multiple pH adjustments.

When this is observed, a flush of the entire system and a thorough cleaning of the reservoir should be implemented. Cleanliness is the best preventative measure for bacteria-caused pH fluctuations.

If plants are still in the system, using a diluted hydrogen peroxide solution is a better choice than bleach because it will not leave behind any harmful residue. Either hydrogen peroxide or a diluted bleach solution can be used to clean hydroponic systems between garden cycles, however.

Growing Medium
Most hydroponic growers use an inert medium in their hydroponic systems. Though usually pH stable, growing mediums can hold nutrients and harbor microbial life that can, in turn, affect the pH of the nutrient solution.

In other words, the growing medium can indirectly affect the pH. Also, growers should not rely on a hydroponic medium to be an effective buffering agent for pH (in nature, soil acts as a large-scale pH buffer). Instead, the medium’s ability to accumulate nutrients and harbor microbes should be taken into account when dealing with pH fluctuations.

Indoor horticulturists should view the nutrient solution’s pH as the determining factor for nutrient uptake. Without a pH within the desired range, plants will not be able to uptake what they need and will suffer because of it.

This is why it is so important for growers to check and recheck their system’s pH value (for hydroponic systems, there is no substitute for the daily monitoring of the system’s pH). Being aware of the most common factors that can influence a solution’s pH will give horticulturists better insight into how to correct or avoid certain pH fluctuations.

Plants love consistency; they thrive on it. The pH of the nutrient solution is no exception. Horticulturists who can maintain a consistent pH within the range where nutrition uptake is maximized will be rewarded with healthier, faster growing plants and larger, more bountiful harvests.

Question I haven't seen asked is are you using C02 enrichment? and if so where is your rez kept is it in the room being enriched? This could be causing your drop in Ph as the rez is becoming more acidic from taking on the C02.

I hope this helps. Peace out
 
RFT

RFT

once you start using all these additives your fighting an uphill battle and probably going to make things worst before they get better.
Im currently using less addititives than ever in my history.

For over a decade my nutrient program was 8-part.

Im down to just an A&B with humics at this point.
 
RFT

RFT

The potential hydrogen, or pH, of a nutrient solution or soil plays a vital role in horticulture. In fact, the pH directly influences whether or not essential elements will be available for uptake by plants.

Before explaining how that works, let’s first look a little closer at pH. On the pH scale, seven is considered neutral. All readings above seven are considered alkaline, and all readings below seven are considered acidic.

The pH scale is an exponential logarithmic scale. In other words, every number on the pH scale represents an increase or decrease of tenfold. For example, a pH value of four is ten times more acidic than a pH value of five and 100 times more acidic than a pH value of six.

The same holds true for readings above seven. For example, a pH value of 10 is 10 times more alkaline than a pH value of nine and 100 times more alkaline than a pH value of eight.

In horticulture, the pH level of a nutrient solution or soil is important because every essential element used by plants has a pH range in which it can be absorbed. If the pH fluctuates too far from that range, a nutrient lockout may occur and cause nutrient deficiencies, hindering the growth and yield of a garden. For most hydroponic gardens, the ideal pH range is between 5.5-5.9. For most soil gardens, the ideal pH range is between 6.3-6.8.

So, what exactly determines the pH of a nutrient solution? The pH of a nutrient solution is influenced by four main factors: the water source, the nutrients, microorganisms (bacteria), and growing medium. It will help a horticulturist greatly if they have a basic understanding of each.


Water Source
When I am asked about the pH of a nutrient solution, I always respond, “consider the source.” The source of the water a grower uses is the number one contributing factor to the nutrient solution’s initial pH and its pH stability over time.

Tap water is probably the worst choice a grower can make in terms of pH stability as it’s full of elements and chemicals that will affect the overall pH of the final solution. Calcium and magnesium are just two of the elements usually found in non-ideal ratios in tap water, contributing to pH fluctuations.

Growers with hard water experience continual problems with pH fluctuations thanks to high concentrations of calcium and magnesium. To remove excess or unwanted elements or chemicals, many hydroponic growers choose to use filtration devices, such as reverse osmosis systems. When done correctly, reverse osmosis will provide a horticulturist with pure water that has a neutral (seven) pH.

Depending on the water’s surrounding environment, the pH can also change over time. For example, when water with a neutral pH is exposed to air, the pH will slowly become more acidic as the water absorbs carbon dioxide from the surrounding air. For most growers, this pH fluctuation is minimal and doesn’t require any further attention.

However, growers who enrich their gardens with high levels of CO2 may experience more dramatic decreases in the system’s pH. The best way to minimize this problem is to remove the reservoir or holding tank from the room that is enriched with CO2.

This way the water in the reservoir is no longer exposed to the high concentrations of CO2. This is also why hydroponic systems where the nutrition solution makes minimal contact with the CO2-enriched growing environment are far less affected by phenomenon.


Nutrients
After securing a relatively balanced water source, growers should examine their nutrients and what effect they make on the solution’s overall pH. One thing to remember is the more nutrients that are added, the more the pH will be impacted.

In other words, if a gardener plans on using a 24-part nutrition regimen, they should plan on taking a lot of time to figure out and balance the solution’s pH.

Once you know how a nutrient affects pH, you can adjust the solution to bring it back to neutral. All adjustments should be made five to 10 minutes after all the nutrients have been added to the water. This will give the solution’s pH some time to stabilize.

Even after making pH adjustments to the solution, however, it’s possible the overall pH will fluctuate over time. As the nutrients break down, some chemical compounds are absorbed by the plant and some are left in the solution.

It’s these unused acidic and alkaline compounds that can cause pH fluctuations. The plants themselves can also affect the solution’s overall pH. As they absorb nutrient ions, they give off ions in return. For example, when a plant absorbs potassium ions, it gives off hydrogen ions that lower the pH.

When a plant absorbs nitrogen ions, it gives off hydroxyl ions that result in a rise of pH. In other words, every chemical reaction happening in a plant’s root mass can potentially affect the pH of the nutrient solution.

Microorganisms (Bacteria)
The countless microorganisms found in the growing medium, reservoir, nutrient solution, and root mass can also affect pH. In most cases, there is no negative effect when these microorganisms are in check. However, certain colonies of bacteria can be the cause of constant downward (more acidic) fluctuations in the solution’s pH.

A good indicator that a bacteria colony is affecting the pH is when the solution’s pH becomes acidic quickly—within a few hours—after initial adjustments have been made. This is especially true if the solution continues to go acidic even after multiple pH adjustments.

When this is observed, a flush of the entire system and a thorough cleaning of the reservoir should be implemented. Cleanliness is the best preventative measure for bacteria-caused pH fluctuations.

If plants are still in the system, using a diluted hydrogen peroxide solution is a better choice than bleach because it will not leave behind any harmful residue. Either hydrogen peroxide or a diluted bleach solution can be used to clean hydroponic systems between garden cycles, however.

Growing Medium
Most hydroponic growers use an inert medium in their hydroponic systems. Though usually pH stable, growing mediums can hold nutrients and harbor microbial life that can, in turn, affect the pH of the nutrient solution.

In other words, the growing medium can indirectly affect the pH. Also, growers should not rely on a hydroponic medium to be an effective buffering agent for pH (in nature, soil acts as a large-scale pH buffer). Instead, the medium’s ability to accumulate nutrients and harbor microbes should be taken into account when dealing with pH fluctuations.

Indoor horticulturists should view the nutrient solution’s pH as the determining factor for nutrient uptake. Without a pH within the desired range, plants will not be able to uptake what they need and will suffer because of it.

This is why it is so important for growers to check and recheck their system’s pH value (for hydroponic systems, there is no substitute for the daily monitoring of the system’s pH). Being aware of the most common factors that can influence a solution’s pH will give horticulturists better insight into how to correct or avoid certain pH fluctuations.

Plants love consistency; they thrive on it. The pH of the nutrient solution is no exception. Horticulturists who can maintain a consistent pH within the range where nutrition uptake is maximized will be rewarded with healthier, faster growing plants and larger, more bountiful harvests.

Question I haven't seen asked is are you using C02 enrichment? and if so where is your rez kept is it in the room being enriched? This could be causing your drop in Ph as the rez is becoming more acidic from taking on the C02.

I hope this helps. Peace out
Great post. Much of this info I’ve been thru adnaseum.

As for your question, Co2 injection is something only recently added to this facility. The pH fluctuations were occurring long before that. And with NFT on scale, there is no way to not expose the solution to open air. In fact, it’s how the system keeps its DO at ample levels.

As for the rest of the post....

Bacteria - this was my first suspect. I’ve eventually settled on calcium hypochlorite. It has kept algae in check and I can only assume it’s not a very bacteria friendly environment.

As said before, this type of system inherently exposes the solution to the air a LOT. By design. Coupd that cause the pH swing? Sure. But then we’d see it earlier in the cycle.

The telling clue here is that it always starts around mid week 4. And that is precisely when the plants have typically started to plateau (Im nor particularly happy with the cola formation). These two issues must be related.

So I lowered my EC. Yet the pH issue persisted.

I could add a pH up doser and let the computers keep everything in balance. But that would only mask whatever the core cause of this is.

At the moment it appears to be the heavy eating and that simply more frequent resi flushes are necessary. Maybe my resi is too small for the number of plants.
 
bigdaddyg8

bigdaddyg8

Great post. Much of this info I’ve been thru adnaseum.

As for your question, Co2 injection is something only recently added to this facility. The pH fluctuations were occurring long before that. And with NFT on scale, there is no way to not expose the solution to open air. In fact, it’s how the system keeps its DO at ample levels.

As for the rest of the post....

Bacteria - this was my first suspect. I’ve eventually settled on calcium hypochlorite. It has kept algae in check and I can only assume it’s not a very bacteria friendly environment.

As said before, this type of system inherently exposes the solution to the air a LOT. By design. Coupd that cause the pH swing? Sure. But then we’d see it earlier in the cycle.

The telling clue here is that it always starts around mid week 4. And that is precisely when the plants have typically started to plateau (Im nor particularly happy with the cola formation). These two issues must be related.

So I lowered my EC. Yet the pH issue persisted.

I could add a pH up doser and let the computers keep everything in balance. But that would only mask whatever the core cause of this is.

At the moment it appears to be the heavy eating and that simply more frequent resi flushes are necessary. Maybe my resi is too small for the number of plants.
did you add plants to your reservoir?
 
Aqua Man

Aqua Man

Staff member
Supporter
Great post. Much of this info I’ve been thru adnaseum.

As for your question, Co2 injection is something only recently added to this facility. The pH fluctuations were occurring long before that. And with NFT on scale, there is no way to not expose the solution to open air. In fact, it’s how the system keeps its DO at ample levels.

As for the rest of the post....

Bacteria - this was my first suspect. I’ve eventually settled on calcium hypochlorite. It has kept algae in check and I can only assume it’s not a very bacteria friendly environment.

As said before, this type of system inherently exposes the solution to the air a LOT. By design. Coupd that cause the pH swing? Sure. But then we’d see it earlier in the cycle.

The telling clue here is that it always starts around mid week 4. And that is precisely when the plants have typically started to plateau (Im nor particularly happy with the cola formation). These two issues must be related.

So I lowered my EC. Yet the pH issue persisted.

I could add a pH up doser and let the computers keep everything in balance. But that would only mask whatever the core cause of this is.

At the moment it appears to be the heavy eating and that simply more frequent resi flushes are necessary. Maybe my resi is too small for the number of plants.
It could definitely be. As the plants eat more you need to do more frequent res changes in order to keep a balanced ratio. This would account for slow down in growth as well as change in ph... But and there always is a but, this could not explain it still happening right after a res change.... Unless (unlike the always a but lol) your issue is from how the nutrients are being added aka dosing pump problems or precipitate
 
RFT

RFT

It could definitely be. As the plants eat more you need to do more frequent res changes in order to keep a balanced ratio. This would account for slow down in growth as well as change in ph... But and there always is a but, this could not explain it still happening right after a res change.... Unless (unlike the always a but lol) your issue is from how the nutrients are being added aka dosing pump problems or precipitate
Im having a hard time going with the theory that the system is doing such a good job delivering nutrients that it needs more frequent flushes.

I’d rather find out I was doing something wrong.

But to add fuel to your theory, the pH drop isnt the next day after a flush. It’s always 2-3 days later. Which would imply heavy wating & imbalance being created.

It does seem to happen quite often (not always) in conjunction with auto dosing as the EC drops.

There is a very likely possibility that auto dosing is throwing ratios offif I dont have the nutrient blend spot on.

And thus full flushes - more often are the only remedy.
 
RFT

RFT

did you add plants to your reservoir?
No I've ran the same number throughout. My reservoir is double the size recommended by the mfg of the NFT system based on this number of plants.

But there is always a VERY strong possibility that the mfg got their calcs wrong and cannabis need larger reservoirs.

I thiught the auto doser would keep things topped off but it is likely causing imbalances.

So maybe more frequent flushes are necessary. It’s very possible.

Theory: resi is big enough while plants are small, then around week 4 at peak height they have outgrown the reservoir’s volume & capability to keep everything fed.
 
Sonnyhad

Sonnyhad

Have a way to track you doser? I might try unplugging it and dosing by hand... Equipment sometimes can fuck ya.
My system is not as big as yours but my auto doser for ph would over shoot some solutions way too much and put my ph out of range one the low end.
 
TheBioMaster

TheBioMaster

Hydroguard should be added every 7 to 10 days.....I'm telling ya bro, the pH stabilizer I mentioned is pretty much made for these type systems and problems.......I speak from years of experience..

What your experiencing is not new at all.......and your not doing anything wrong per say.

I would defiantly look into the possibility that your auto doser is the culprit as suggested.

I'm sure you will get it worked out!
 
Last edited:
RFT

RFT

Hydroguard should be added every 7 to 10 days.....I'm telling ya bro, the pH stabilizer I mentioned is pretty much made for these type systems and problems.......I speak from years of experience..

What your experiencing is not new at all.......and your not doing anything wrong per say.

I would defiantly look into the possibility that your auto doser is the culprit as suggested.

I'm sure you will get it worked out!
A stabalizer just treats the symptom.

I want to get to the bottom of why the pH dives during specific weeks.

And no, it’s not the auto doser.
 
FamilyCanna

FamilyCanna

My thoughts on this -

I have a background in large-scale marine aquariums and coral reef systems. You very quickly learn that your hobby is NOT keeping animals and plants, but rather keeping perfect water chemistry.

The simple answer that was mentioned only once in this entire thread is this - unless you know EXACTLY what is happening in your water chemistry, you are just guessing and taking shots.

As with all life/water/nutrient relationships, there is an unspoken caveat that must exist, the role of God or Mother nature - an ongoing "keeper" of the status quo. On earth, this is a system so complex that the outcome is life itself.

In hydroponics, or any other system in which you want to recreate or modify nature, YOU play that hidden role. It's neverending and ongoing.

When you create your growing media, whether it be water, soil, etc. There is a give/take with every single element involved. Your plants being the biggest contributor.

As your plants interact with the nutrient solution, the chemistry is violently changing on the micro level. For instance as calcium is depleted, magnesium uptake increase to balance it back out, maintaining a seesawing type action until the levels are reduced to the point of atrophy within the cell walls of the plant.

All this give/take between the plant and the water column will fluctuate throughout the day and the entirety of the grow based on dozens of variables from from bacterium within the water, light, temp, atmosphere, etc.

This is literally why dosing/automation. systems alone are a $200m industry.

Cannabis is a forgiving plant, it is up to you to check daily, or even multiple times per day to ensure they are living within the desired parameters.

Multiple small changes vs fast huge changes are key.

Here is a phrase you should memorize
- Nothing Good Happens Fast -

Peace and love.
 
FamilyCanna

FamilyCanna

My system is not as big as yours but my auto doser for ph would over shoot some solutions way too much and put my ph out of range one the low end.
Always best to run ph up/down dilutions via doser, not solution.

When you add pure or highly concentrated acid or alkaline, it will either precipitate out immediately, or in your case not accurately dose in the first place.

The displacement of 2ml of acid in a res of say 20g wont mix efficiently, or more likely, cling to heavy alkaline radicals within the column and fall sediment.

With a dilution, you increase the same 2ml acid to say a 50ml dilution, it mitigates precipitation and instant binding.

Cheers.
 
RFT

RFT

My thoughts on this -


As your plants interact with the nutrient solution, the chemistry is violently changing on the micro level. For instance as calcium is depleted, magnesium uptake increase to balance it back out, maintaining a seesawing type action until the levels are reduced to the point of atrophy within the cell walls of the plant.

All this give/take between the plant and the water column will fluctuate throughout the day and the entirety of the grow based on dozens of variables from from bacterium within the water, light, temp, atmosphere, etc.
You sound credible.

The comments I've quoted are of note to me.

What are your theories as to the issues Im having?

Should I just chalk up the pH fluctuations to "business as usual" and immediately flush the reservoir as some have suggested? If that was the case, wouldnt EVERYONE have these pH drops?

Should I pull a sample the next time it drops to get the nutrient solution tested? Would that give me a better indication of what was actually happening?

Im all ears.
 
Sonnyhad

Sonnyhad

Always best to run ph up/down dilutions via doser, not solution.

When you add pure or highly concentrated acid or alkaline, it will either precipitate out immediately, or in your case not accurately dose in the first place.

The displacement of 2ml of acid in a res of say 20g wont mix efficiently, or more likely, cling to heavy alkaline radicals within the column and fall sediment.

With a dilution, you increase the same 2ml acid to say a 50ml dilution, it mitigates precipitation and instant binding.

Cheers.
Nice bit of info, thank you kindly!
 
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