Carbocalcium and pH

Randy Holmes-Farley

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Can you link me to a study showing this, or explaining it? So far i have not found any data to show this occurring.

OK, I'll try explaining again. You linked an earlier thread of mine where I discussed how acetate dosing lowers pH and why. That's a fine place to start. Formate is a smaller effect, but in the same direction.

The equation I posted above shows that from a pH perspective, formate dosing for alkalinity it is exactly the same as dosing bicarbonate.

I show in this article below how different alkalinity additives (bicarbonate, carbonate, and hydroxide) impact pH, and this is the bicarbonate section:


Bicarbonate Addition
The addition of bicarbonate as an alkalinity supplement is rather different. In this case, the bicarbonate partially dissociates into carbonate and H+, and the tank experiences an increase in bicarbonate and carbonate, and a drop in pH.:

15. HCO3– → H+ + CO3—

Consequently, the immediate effect on pH is for it to drop. The drop is small because not much of the bicarbonate dissociates at normal tank pH, but enough does to drive the pH a bit lower (from 8.10 to 8.06 in the experiment above).

In the long term, however, the effect is different. Since a substantial amount of bicarbonate was added and the pH did not change much, the tank is now overloaded with bicarbonate with respect to what it would normally have in equilibrium with air. Some of the bicarbonate picks up a proton, becomes carbonic acid, and the pH rises as the CO2 is blown off to the atmosphere:

16. HCO3– + H+ → H2CO3 → CO2 + H2O

In the experiment above, this effect has caused the pH to rise from 8.06 to 8.33. So the long-term effect of bicarbonate addition (as it is for any addition to carbonate alkalinity) is to raise pH even though the short-term effect was to lower it.
 
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Shooter6

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OK, I'll try explaining again. You linked an earlier thread of mine where I discussed how acetate dosing lowers pH and why. That's a fine place to start. Formate is a smaller effect, but in the same direction.

The equation I posted above shows that from a pH perspective, formate dosing for alkalinity it is exactly the same as dosing bicarbonate.

I show in this article below how different alkalinity additives (bicarbonate, carbonate, and hydroxide) impact pH, and this is the bicarbonate section:


Bicarbonate Addition
The addition of bicarbonate as an alkalinity supplement is rather different. In this case, the bicarbonate partially dissociates into carbonate and H+, and the tank experiences an increase in bicarbonate and carbonate, and a drop in pH.:

15. HCO3– → H+ + CO3—

Consequently, the immediate effect on pH is for it to drop. The drop is small because not much of the bicarbonate dissociates at normal tank pH, but enough does to drive the pH a bit lower (from 8.10 to 8.06 in the experiment above).

In the long term, however, the effect is different. Since a substantial amount of bicarbonate was added and the pH did not change much, the tank is now overloaded with bicarbonate with respect to what it would normally have in equilibrium with air. Some of the bicarbonate picks up a proton, becomes carbonic acid, and the pH rises as the CO2 is blown off to the atmosphere:

16. HCO3– + H+ → H2CO3 → CO2 + H2O

In the experiment above, this effect has caused the pH to rise from 8.06 to 8.33. So the long-term effect of bicarbonate addition (as it is for any addition to carbonate alkalinity) is to raise pH even though the short-term effect was to lower it.
I understand the effects from bicarbonate calcium dosing, that has been well established for many years. Probably since before either of us have been reefing.
This is a different form of calcium, calcium formate.
Calcium acetate effect on ph is in the link i posted above, showing the acid causing the change in ph. I still have not found any study showing the formate lowering ph.
 

Lou Ekus

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I understand the effects from bicarbonate calcium dosing, that has been well established for many years. Probably since before either of us have been reefing.
This is a different form of calcium, calcium formate.
Calcium acetate effect on ph is in the link i posted above, showing the acid causing the change in ph. I still have not found any study showing the formate lowering ph.
I think what @Randy Holmes-Farley is trying to say, is that the effect of calcium formate is "similar" to what you might see with calcium acetate. The difference is that the effect in both the carbon dosing aspect and the pH aspect is such a small fraction of what you will see from a calcium acetate addition, that it is mostly inconsequential. In fact, it will be so small, that it will even be difficult to detect at all.

The reason you are not finding a lot of studies or information about the interactions of calcium formate in reef tanks is because the technology is very new. We have certainly looked at this very carefully in our Tropic Marin laboratory, but we have not yet published papers about it. By the way, we are working on that too! :)
 

Shooter6

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I think what @Randy Holmes-Farley is trying to say, is that the effect of calcium formate is "similar" to what you might see with calcium acetate. The difference is that the effect in both the carbon dosing aspect and the pH aspect is such a small fraction of what you will see from a calcium acetate addition, that it is mostly inconsequential. In fact, it will be so small, that it will even be difficult to detect at all.

The reason you are not finding a lot of studies or information about the interactions of calcium formate in reef tanks is because the technology is very new. We have certainly looked at this very carefully in our Tropic Marin laboratory, but we have not yet published papers about it. By the way, we are working on that too! :)
Glad to hear that last part.

Then if the in ability to measure any effect on ph is the case, in the end there is none, and that circles back to what i originally said. If the op is seeing a drop in ph its more then likely due to other factors, not carbocalcium or afr.

Randy said originally that yes i is lowering ph, but then has walked back on that statement through his final statements.
 

arking_mark

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Love the pH discussion. My understanding is that CO2, Alk, and pH have a known relationship in seawater. Alk is mostly a measure of Carbonate and Bicarbonate for practical purposes.

Screenshot 2021-05-04 154104.png


If you add Carbonate (CO3) Bicarbonate (HCO3) to tank water at a given CO2 level, the % of Carbonate and Bicarbonate is increased (increased ALk) which should raise pH.

Per Randy, Formte metabolizes to:
2HCO2- + O2 --> 2CO3-- + 2H+

So we have increased Alk and H. It seems that the added H (lower pH) may be offset by the increased Alk.

If Calcium Formate is just replacing Alk consumption then there should be a net lowering of pH. However, I believe this lowering effect will be muted by the fact that added CO3 will rebalance in the tank with HCO3 which will consume some of the added H.
 
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arking_mark

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Love the pH discussion. My understanding is that CO2, Alk, and pH have a known relationship in seawater. Alk is mostly a measure of Carbonate and Bicarbonate for practical purposes.

Screenshot 2021-05-04 154104.png


If you add Carbonate (CO3) Bicarbonate (HCO3) to tank water at a given CO2 level, the % of Carbonate and Bicarbonate is increased (increased ALk) which should raise pH.

Per Randy, Formte metabolizes to:
2HCO2- + O2 --> 2CO3-- + 2H+

So we have increased Alk and H. It seems that the added H (lower pH) may be offset by the increased Alk.

If Calcium Formate is just replacing Alk consumption then there should be a net lowering of pH. However, I believe this lowering effect will be muted by the fact that added CO3 will rebalance in the tank with HCO3 which will consume some of the added H.

@Randy Holmes-Farley I'm curious if I got the chemistry right or if my understanding is still off.
 

Randy Holmes-Farley

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I understand the effects from bicarbonate calcium dosing, that has been well established for many years. Probably since before either of us have been reefing.
This is a different form of calcium, calcium formate.
Calcium acetate effect on ph is in the link i posted above, showing the acid causing the change in ph. I still have not found any study showing the formate lowering ph.

The only link that I see you posted on calcium acetate is my own writing, I think. Was there something else?

Neither calcium acetate nor calcium formate will have any impact on the pH of seawater when first added. The pKa values are much too low for any significant amount to be protonated and so there is NO pH effect when added.

The pH effect of both come when it is metabolized. Same for ethanol/vodka. It has ZERO pH effect when added, but certainly lowers pH when metabolized to CO2. Do people see that effect? Some may and many may not. IT is widely spread out and on the low side.
 

Shooter6

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The only link that I see you posted on calcium acetate is my own writing, I think. Was there something else?

Neither calcium acetate nor calcium formate will have any impact on the pH of seawater when first added. The pKa values are much too low for any significant amount to be protonated and so there is NO pH effect when added.

The pH effect of both come when it is metabolized. Same for ethanol/vodka. It has ZERO pH effect when added, but certainly lowers pH when metabolized to CO2. Do people see that effect? Some may and many may not. IT is widely spread out and on the low side.
The one iposted doesnt appear for some reason.



These were im my post that doesnt appear..
 

Randy Holmes-Farley

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Glad to hear that last part.

Then if the in ability to measure any effect on ph is the case, in the end there is none, and that circles back to what i originally said. If the op is seeing a drop in ph its more then likely due to other factors, not carbocalcium or afr.

Randy said originally that yes i is lowering ph, but then has walked back on that statement through his final statements.

As a friendly service to you, I have tried over and over to explain to you how calcium formate MUST lower pH. Don't put words in my mouth if you want any more expert chemistry knowledge from me. If you just want a fight, move along. If you just want to continually point out to a nationally recognized expert chemist with a PhD from Harvard that formate and bicarbonate are different chemicals, move along. if you want to learn, I'm more than happy to help and maybe lean things as well.

Just like bicarbonate, formate added as an alkalinity supplement MUST lower pH.

Must it be a big drop? Of course not. Must people even detect it? Of course not.

Must if be exactly the same as if bicarbonate was dosed at the same rate the formate is metabolized? Yes.

Is that effect enough to explain the OP results? Certainly could be.

This is exactly what I said, and I stand by it as 100% correct:

"Yes, it will tend to lower pH a little bit, where other supplements you may have switched from may tend to raise pH (carbonate or hydroxide)."
 

Randy Holmes-Farley

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The one iposted doesnt appear for some reason.



These were im my post that doesnt appear..

The pH of those solutions is not material to the discussion. Formate added to a reef tank does nothing until it is chemically changed. Likewise, vodka is not acidic, but when the ethanol is metabolized in a reef tank lowers pH by producing CO2.
 

Shooter6

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As a friendly service to you, I have tried over and over to explain to you how calcium formate MUST lower pH. Don't put words in my mouth if you want any more expert chemistry knowledge from me. If you just want a fight, move along. If you just want to continually point out to a nationally recognized expert chemist with a PhD from Harvard that formate and bicarbonate are different chemicals, move along. if you want to learn, I'm more than happy to help and maybe lean things as well.

Just like bicarbonate, formate added as an alkalinity supplement MUST lower pH.

Must it be a big drop? Of course not. Must people even detect it? Of course not.

Must if be exactly the same as if bicarbonate was dosed at the same rate the formate is metabolized? Yes.

Is that effect enough to explain the OP results? Certainly could be.

This is exactly what I said, and I stand by it as 100% correct:

"Yes, it will tend to lower pH a little bit, where other supplements you may have switched from may tend to raise pH (carbonate or hydroxide)."
Sorry if i ruffled your feathers or offended you. Im glad you have a phd from Harvard, i recover personnel and equipmet from austere locations, mith a minor in making things go boom.

Now to get back to my conversations with you, i asked you for the studies or science behind your first statement to the op. I did so as my 2.5 years of actual use of the product shows different results from your first statement. I showed where i tried to find info that supported your statement as i do not believe i know it all and glady will take any factual info i can on any product.
In the end we came to a mutual agreement that it may be possible it lowers the ph ,to some extent, but also probably not to a detectable level.
Then i guess you felt a need to back awY from that as you feel offended.

Again sorry if i was to abrasive for you, i live in a different world from you.
 

deepgreen

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Sorry if i ruffled your feathers or offended you. Im glad you have a phd from Harvard, i recover personnel and equipmet from austere locations, mith a minor in making things go boom.

Now to get back to my conversations with you, i asked you for the studies or science behind your first statement to the op. I did so as my 2.5 years of actual use of the product shows different results from your first statement. I showed where i tried to find info that supported your statement as i do not believe i know it all and glady will take any factual info i can on any product.
In the end we came to a mutual agreement that it may be possible it lowers the ph ,to some extent, but also probably not to a detectable level.
Then i guess you felt a need to back awY from that as you feel offended.

Again sorry if i was to abrasive for you, i live in a different world from you.
I also have a degree in making bad guys go away and now I teach young pups like you how to do the same.
That does not mean I feel privileged enough to throw someone’s expertise and help back in their face. You asked for information. You got it. You asked for expert evidence. You got it.
 

Randy Holmes-Farley

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I'm curious if I got the chemistry right or if my understanding is still off.

I think the easiest way to look at it is by looking at what the formate must turn into first to be used in calcification by a coral, and looking at that conversion, what else (if anything) is produced.

In the case of acetate, there is both CO2 and bicarbonate made, so the effect of pH lowering comes from both the CO2 and the bicarbonate since both are known to, and are easily shown to, reduce pH when added to seawater.

In the case of ethanol for organic carbon dosing, there is only CO2 produced and the pH is lowered for that reason. In this scenario, the pH effect is highly spread out, but still is a lowering.

In the case of formate, we get the bicarbonate produced, but not the CO2, so only the bicarbonate is contributing to the pH lowering. The amount of pH lowering from bicarbonate is well understood, both experimentally and theoretically, but it is widely spread out in time when coming from metabolized formate, so a reef cannot just see a sudden drop and attribute to to the dosing.

The usual recommended way of dosing carbocalcium doesn't raise alkalinity, so the effect on pH from raised alkalinity (such as is seen from bicarbonate where the pH drops from alla t once dosing, but then later rises to attain a higher pH due to the higher alk level by the tank driving off some CO2) will not be observed.

Certainly, if you dose enough carboncalcium that the alkalinity actually ends up higher than previously, then yes, you may see the pH rise from increased alkalinity, just as you would with any pH raising or lowering alkalinity additive.

Hope that helps.
 

Randy Holmes-Farley

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Now to get back to my conversations with you, i asked you for the studies or science behind your first statement to the op. I did so as my 2.5 years of actual use of the product shows different results from your first statement. I showed where i tried to find info that supported your statement as i do not believe i know it all and glady will take any factual info i can on any product.
In the end we came to a mutual agreement that it may be possible it lowers the ph ,to some extent, but also probably not to a detectable level.

I certainly have no issue with folks stating that they use it and see no pH drop. That may be the most common occurrence.

I also think that my answer to the OP was perfectly correct and accurate, and I stand by it.
 
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Randy Holmes-Farley

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1620226103103.png

Am I wrong that an addition of HCO3- will buffer seawater at pH 8.0? :)

Adding bicarbonate to seawater reduces the pH a little bit immediately because some portion of it splits into H+ and CO3-- by Le Chatlier's principle:

HCO3- --> CO3-- + H+

The lower the initial pH, the smaller is the amount of carbonate at equilibrium, and hence the less is converted to H+ and carbonate.

The effect I measured (a drop of 0.04 pH units) was at a starting pH of 8.10. At pH 8.0 the effect is smaller, but even at pH 7.8 it will still tend to lower pH.

The effect will not reverse direction with lowering pH until more bicarbonate is converted into CO2 (raising pH) than is converted into carbonate (lowering pH).

HCO3- + H+ --> H2CO3

That reversal is likely to happen at about pH 7.4, which is mid way between between the two pKa values for carbonic acid (about 5.8) and bicarbonate (8.9).
 

GlassMunky

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I dose 10ml every hr. With no measurable ph drop. That is comparing 3 years of redsea 3 part, to 2.5 years of afr.
I dont believe my system is more highly aerated in comparison to most others. Im about average.
Are people seeing this drop by manual dosing a large amount only once a day?
Im going to ask the tm U.S. rep his opinion on this as nobody else ive spoken with who use afr have had this come up.
So I have 1 tank that uses carbocalcium as supplements and another tank that doesn’t dose anything. Both tanks in roughly the same area of the house. My tank that gets doser with carbocalcium stays at around 7.8-8.0 ph night/day.
My other tank that doesn’t get dosed anything is constantly at 8.0-8.3
Only difference is one gets dosed the other doesn’t.

now while the ph of both tanks is “stable” the one that gets the carbocalcium is always lower so take what you will from that.
 

arking_mark

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So I have 1 tank that uses carbocalcium as supplements and another tank that doesn’t dose anything. Both tanks in roughly the same area of the house. My tank that gets doser with carbocalcium stays at around 7.8-8.0 ph night/day.
My other tank that doesn’t get dosed anything is constantly at 8.0-8.3
Only difference is one gets dosed the other doesn’t.

now while the ph of both tanks is “stable” the one that gets the carbocalcium is always lower so take what you will from that.

How identical are the tanks? If one is heavily stocked with fish which produce CO2...
 
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