# Low KH and pH crash



## Edward

Fiki said:


> What I want to say is that, due extremely low buffer capacity such as kH zero, pH value simply can not be stabile, especially if you use pressurized CO2 at the same time. Therefore, I've been trying to avoid often fluctuation of pH caused by buffer insufficiency in aquarium water, as they can cause a lot of problems regarding the fishes health and possible stress. In addition, I would appreciate if you could make a short list of aquatic plants and fishes that you successfully grow at KH zero, using the CO2 injection at the same time.


 Personally, I am not sure if the CO2 tables we use are correct. After spending years chasing KH, CO2 and pH I found easier way. No KH buffering, no pH testing and no sick fish and plants. Actually, fish are much happier and plants grow even healthier. The plant list includes several dozen plant species from Echinodorus and Cryptocoryne to Wallichii and Toninas. Never had a plant that wouldn't like it. Lower the KH nicer the plant.

Fish I have are Tetras, Angels, Altums and Discus, naturally soft water fish. Brackish and Tanganyikan Cichlids are not compatible of course.

Generally fish don't like pH changes and high CO2. The actual pH doesn't matter. CO2 is natural to the fish. It creates stability at pH ~ 5.6. It never goes bellow 5 or so. (As an experiment I added peat moss to lower it even more, bellow CO2 capacity of 5.65 to 3.7 and still no problem)

We can not stress more the need to use CO2 only. No other acids are safe. 
If you see your fish in stress or dead then it is due to high CO2, poison or non CO2 acid.



banderbe said:


> Hi Edward. How do you avoid the dreaded pH crash? Or is that just another myth?


 Can you define such crash? 
What we see is CO2 overdose not pH crash. It is the CO2 killing the fish not the low pH.

Tropical rainy season removes carbonates (KH) buffering and takes large amounts of humic and carbonic (CO2) acid. Are there casualties because of some pH crash? No.

We shouldn't be afraid exploring more natural approach growing fish and plants in our aquariums.

Thank you
Edward


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## hoppycalif

Great post Edward! Your explanation fits all of the facts I know of. You say you don't think the pH/KH tables give good numbers for CO2 - I agree with that. How do you measure or estimate how much CO2 you have in the water?


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## Edward

hoppycalif said:


> Great post Edward! Your explanation fits all of the facts I know of. You say you don't think the pH/KH tables give good numbers for CO2 - I agree with that. How do you measure or estimate how much CO2 you have in the water?


Thank you hoppycalif
Not knowing the CO2 level worried me for some time. When everything was growing well I couldn't test it due to the KH being at zero. One dose of baking soda exposed the probable CO2 level of 10-15 ppm. This was enough under high light 6 Watts per gallon PC.

Here are the CO2 rates:
10 gall => 10 bubbles / min
50 gall => 50 bubbles / min
100 gall => 100 bubbles / min

I would like to add that tiny aeration is beneficial when fish is in the aquarium.

Thank you
Edward


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## Krisybabe9

I like the idea and the information that you posted.
I'm interested in giving it a shot.

I currently buffer with baking soda. How would I go about making the change in such a way that avoids fish stress? Anytime I try to reduce the amount of buffer I add my fish gasp at the surface.


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## Glouglou

*PH crash is not a mith.*

What is "pH crash?" Simply, this is when the buffers in your water are all used up and the pH of the water plummets. This is not good for the tank inhabitants or the biofilter. Many of the nitrifying bacteria are inactive at a pH below 6.0.

It happen to my tank and my Hagen KH test at this time show around 1 mg/l.

My Ph went to around 5 in matter of hours.
Liquid CaCo3 was administered, no fish loss.

I was working with Hagen CO2 system at that time, I, only in rare occasion manage to have around 20mg/l of CO2.


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## Bert H

Edward, help me understand here. Are you saying that in your opinion/experience the actual pH is not important (as long as it doesn't drop below 5), but stability is the important factor? A bubble rate of approx 1 per second in your 50 gives you a pH of 5 and fish and plants are happy?


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## Edward

Krisybabe9 said:


> Anytime I try to reduce the amount of buffer I add my fish gasp at the surface.


All of my 13 aquariums don't have any pH buffers and KH and still, I never see any fish gasping for air. All tanks run CO2.

What kind of fish do you have?


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## Edward

Bert H said:


> Edward, help me understand here. Are you saying that in your opinion/experience the actual pH is not important (as long as it doesn't drop below 5), but stability is the important factor? A bubble rate of approx 1 per second in your 50 gives you a pH of 5 and fish and plants are happy?


Sure the pH can go bellow 5 that is not a problem. I am saying that the pH due to CO2 will stop at around 5. 
I had a group of 8 Tetras in pH of 3.7 for 3 years. Peat addition with CO2 pushed the pH that low. They multiplied to 20 fish on their own. I still have them today in the same aquarium. Very healthy fish.

People think when fish die due to pH rapid change from 8 to 5 that the reason is the 5. This assumption is wrong. If the pH changes from 5 to 8 the fish will also die. The rate of change is the reason, not the actual pH.

I no longer test for pH because it is irrelevant. The fish don't care.

Thank you
Edward


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## chiahead

Edward just curious do you shut the Co2 off at night or leave it on 24/7?


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## Edward

chiahead said:


> Edward just curious do you shut the Co2 off at night or leave it on 24/7?


Hi chiahead
Good you asked because I see a potential problem with turning the CO2 off at night. Look how many hours it takes to get CO2 out of water. In this great post #1 by hoppycalif:
http://www.aquaticplantcentral.com/forumapc/science-of-fertilizing/26816-some-co2-relevant-data.html
It must take a long time to get it back in.

This is why I let the CO2 on continuously 24/7 without interruption.

Thank you
Edward


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## chiahead

whenever I leave my co2 on 24/7 when I wake up the fish are gasping at the surface. I guess how youi get around it is lower the buble rate a bit so les Co2 gets in the tank but spread over the whole day so its all balanced. Interesting thought. That should keep it pretty stable. Doesnt the ph change a bit during the peak photo period when the plants are consuming co2?


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## Edward

chiahead said:


> whenever I leave my co2 on 24/7 when I wake up the fish are gasping at the surface. I guess how youi get around it is lower the buble rate a bit so les Co2 gets in the tank but spread over the whole day so its all balanced. Interesting thought. That should keep it pretty stable. Doesnt the ph change a bit during the peak photo period when the plants are consuming co2?


You don't run air stone, do you? There should be an air stone if there is fish to exchange gasses and keep the water fresh. Adjust it to the minimum possible flow. I haven't notice pH fluctuations.


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## AaronT

Edward said:


> You don't run air stone, do you? There should be an air stone if there is fish to exchange gasses and keep the water fresh. Adjust it to the minimum possible flow. I haven't notice pH fluctuations.


So you are running an airstone and CO2 both on lower levels 24/7? That's a very interesting approach. I may have to try that sometime.

Are you using RO water to get a KH of 0 and then adding only GH back for the plants?


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## Bert H

This is a very interesting thread in that it proposes things that most do not do. 

-A kh of 0, with CO2 injection
-pH of 5 or lower
-24/7 CO2 on a low kh tank
-airstone while CO2 is on not affecting CO2 levels.

This really points out how many different ways there are to achieve success in our chosen pursuits in this hobby. 

I wonder how many other folks are running a similar set up?


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## AaronT

I thought of another question in the meantime. Are you able to keep shrimp in pH that low? Many of us keep Neocaridina and Caridina shrimp that are said to need a pH of 6.5-7.0 or so.


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## Edward

AaronT said:


> Are you using RO water to get a KH of 0 and then adding only GH back for the plants?


Yes that's right, RO with CaCl2 at 20 ppm Ca. For Mg dosing PPS Mg solution.


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## hoppycalif

AaronT said:


> I thought of another question in the meantime. Are you able to keep shrimp in pH that low? Many of us keep Neocaridina and Caridina shrimp that are said to need a pH of 6.5-7.0 or so.


It used to be said that....phosphate causes algae, nitrate is poison, you gotta have red clay under the substrate, some plants have to have root feeding, etc. I suspect that those who say pH of 6.5-7.0 is needed for some animal life, whether shrimp or discus, or whatever, are just repeating what somebody told them. I know my cherry shrimp are doing very well and my pH varies quite a bit from water change to water change, so I suspect that shrimp react to dissolved solids and not pH, just as fish do.


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## Edward

AaronT said:


> Are you able to keep shrimp in pH that low? Many of us keep Neocaridina and Caridina shrimp that are said to need a pH of 6.5-7.0 or so.


Not sure. I don't have shrimps. 
The low KH aquarium is not for Brackish and Tanganyikan fish.


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## Zapins

Hmm, this is very interesting. I have a KH of 0 naturally from the tap. However, my plants showed signs of Co2 deficiency when the pH reached ~5. Since then I have been buffering the water to about 4 degrees, and have been cautious of raising it higher. I was using a pH controller at the time. 

Do you think that the controller was the problem because it does not take much Co2 to maintain a pH of 5 with 0 KH (hence the deficiency)? If so, are pH controllers useless if using 0 KH?

As an after thought, are there any strong benefits to keeping a KH of 0 vs. keeping it at 1-3? You mentioned plants grow better, exactly how do they grow better?


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## Robert Hudson

It is much more common for people to have hard to very hard water out of the tap than soft water. So would you not agree if you have fairly hard water and are not adding anything to change the KH, then you can get a pretty accurate reading using a KH/pH chart right?



> Not sure. I don't have shrimps.


You must not have any snails either. Shrimp, snails, need high levels of calcium


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## Laith

Robert Hudson said:


> ...So would you not agree if you have fairly hard water and are not adding anything to change the KH, then you can get a pretty accurate reading using a KH/pH chart right?
> ...


Not necessarily and this is the problem with the chart. The chart relies on KH being made up mainly of either carbonates or bicarbonates (I don't remember which one offhand). There are tap waters where the make up of the KH is such that it makes the chart invalid.


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## Edward

Zapins said:


> Hmm, this is very interesting. I have a KH of 0 naturally from the tap. However, my plants showed signs of Co2 deficiency when the pH reached ~5. Since then I have been buffering the water to about 4 degrees, and have been cautious of raising it higher. I was using a pH controller at the time.
> 
> Do you think that the controller was the problem because it does not take much Co2 to maintain a pH of 5 with 0 KH (hence the deficiency)? If so, are pH controllers useless if using 0 KH?
> 
> As an after thought, are there any strong benefits to keeping a KH of 0 vs. keeping it at 1-3? You mentioned plants grow better, exactly how do they grow better?


Hi Zapins
The CO2 deficiency was due to the design of the CO2 Controller, because it is based on pH instead of the real CO2 concentration. I think simple needle valve would do the job more reliably.

There is nothing wrong with KH of 1 or 2 degrees except that it is difficult to maintain at stable level for long. And I noticed some sensitive plants need more light to grow as nicely at higher KH and some don't grow at all.

Thank you
Edward


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## dstephens

Guys, I have a situation that fits into this discussion somewhere. I have a 90 gallon planted tank that has approx. 4.2 watts per gallon, injected CO2 and I have been using a Milwaukie PH monitor to control the CO2. The KH runs around 4 most of the time. My PH has been running around 6.2 - 6.4 for weeks. In other words, because every time the CO2 runs, it blows the PH down quickly and the controller shuts off at 6.2. The plant growth has been minimal and I don't see any pearling at all. After reading this thread I decided to turn the bubbles up, lower the PH threshold and monitor the situation to make sure I don't nuke my fish. So far, I have managed it downward to a PH of 5.8 before the fish start moving towards the surface. Now the PH is hovering around 5.8 - 5.9. At a KH of 4, that would put the 
CO2 measurement through the roof using the KH/PH CO2 Chart. I still don't see any pearling on the plants. I also dose flourish excel and other seachem ferts for macros and micros. The palnts look great and I know they are growing but I'm not seeing the kind of growth or pearling that I have seen in the past using injected CO2. Also, will my fish eventually adjust to the lower PH? Any suggestions? Thanks for letting me jump in here. Darrell


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## Edward

Robert Hudson said:


> It is much more common for people to have hard to very hard water out of the tap than soft water.


 Hi Robert, 
Where are the most beautiful planted aquariums? From Thailand, Indonesia, Singapore, Malaysia to Japan. Why? One of the reasons is they enjoy very low KH and GH of 0 to 1 degree.



> So would you not agree if you have fairly hard water and are not adding anything to change the KH, then you can get a pretty accurate reading using a KH/pH chart right?


 Looks like no one is really sure.



> You must not have any snails either. Shrimp, snails, need high levels of calcium


 Yes I have snails. KH and Ca are not related. You can have zero KH and 15 ppm Ca (2 degrees GH) and still have nice snails. Or if you like, zero KH and 30 ppm Ca (4 degrees GH).

Thank you
Edward


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## Edward

dstephens said:


> After reading this thread I decided to turn the bubbles up, lower the PH threshold and monitor the situation to make sure I don't nuke my fish. So far, I have managed it downward to a PH of 5.8 before the fish start moving towards the surface. Now the PH is hovering around 5.8 - 5.9. At a KH of 4, that would put the
> CO2 measurement through the roof using the KH/PH CO2 Chart. I still don't see any pearling on the plants.


 That makes 190 ppm CO2. You are killing your fish. Please note that we are discussing zero KH conditions, not 4 KH. Lower the CO2 ASAP.



> Also, will my fish eventually adjust to the lower pH


 If they are not high pH fish then yes they will adjust. But they will not adjust to CO2 over 30 ppm.

The reason why your plants are not pearling is possibly too many hours of light a day or some nutrient deficiency. And plants don't need to pearl to grow well.

Thank you
Edward


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## dstephens

I just recalibrated my PH monitor and the probe was off by .5! I checked the PH with a test kit and it is approximately 6.4, so, a little better than 5.9. I will back off the CO2 and check the other parameters to see if there is a deficiency of some kind. Thank you for the quick response. I turned the air diffuser on and that should help the fish recover. Darrell


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## Avalon

Hi Darrell. I've got a small tank with water param's close to yours. I found that dumping in CO2 doesn't help, and you certainly can't keep fish (my tank only has 1 lone oto cat). There's a certain range, within roughly 0.2-0.4 ph that you can work in without having algae issues. The success with such casual measurements lies within the lighting. Use less (duration or intensity), and you will lessen the need for CO2, although I have found that less intensity works better. My plants don't pearl at all under 6.5 wpg, but I'm growing Tonina belem and manaus like a champ.

I'm very interested in this low-to-no KH thing. I usually get a 2-4 dKH reading from mixing RO with tap, but I've never really checked after the drop from the Florabase substrate. I assume it will drop the KH 2-3 degrees. But it appears that the longer I go without a w/c, the better my plants look. My little oto doesn't seem to mind, but when the CO2 was high he sure did. I cut the amount of CO2 in half and he seems fine now, and my plants are still growing well (except for my L. pantanal with broad leaves, but it still grows like it was supposed to have them).

I set up my little 10g tank (I usually keep large ones) to experiment with. Right now it's for soft water, since I have liquid rock flowing from my tap. You can grow many a plant in very hard water, but it can be very difficult, particularly with large aquariums (75g and over). If you want high light, you need tons of CO2, which can harm fish. Low light works much better. My next (continuing) experiment in my little tank will be the PPS. If I can figure out how to keep higher light, soft water plants, and not have to change RO water in a larger tank very often, I will have entered planted tank nirvana!


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## dstephens

This has been an interesting ride for me and part of the problem is that I am not thinking things through enough. My tank looked so good for so long that I took it for granted that things would stay that way. Felt like I could grow anything and wow, have I had some disasters. I have a 90 gallon planted and I started it 7 months ago. Lot's of fast growing stems, CO2 was jamming away, PH consistent around 6.7 -6.9, not much algae problems. Then I decided to pull stuff out and start trying difficult plants without giving a lot of consideration to the parameters that work best for a specific plant, or grouping of plants, spent too much money buying plants....... 

Anyway, I learned a great deal from folks like yourself on the APC forums. I really like the look of my tank now but I have been trying to force this CO2 issue. I have a large area newly planted with HC and I'm trying to bump the CO2 to enhance whatever chances I have of getting the HC to take hold and take off. I currently run my lights about 11-12 hours a day. I have 390 watts of PC 6700k lights over 90 gallons. Injected CO2. In the past I have run the air diffuser at night to hedge against any issues with the fish. I have always had a pearling effect, up until now, and that makes me think that my growth has diminished and I have green dust/brown crusty algae on the glass. I also dose excel, nitrogen, potassium, flourish, phosporus, iron and trace elements. I keep the temp around 76-78.5. PH 6.5 - 6.8. recently, the PH has been creeping downward. I change 20 gallons or so every week. I probably have 70 nominal gallons considering all of the substrate, which is flourite. KH of 3.5 - 4.5. I don't check the others very often, usually going on the visual to see how things are going. I also have a UV sterilizer in-line. Anyway, that's the ticket. 

I don't see or really have any major issues. I would just like to grow my plants to their optimal capacity. I am really sorry if it seems like I have highjacked somone else's thread. I should be calling Dr. Phil maybe instead of all this blabber. Always open to feedback/suggestions. Thanks for letting me share. Darrell


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## Robert Arnold

I have some HC in some flourite which is starting to really take. Actually, everything in that tank is doing well. The tank had half new and half 4 year old flourite which I gravel vaccumed pretty well before starting this new 65 gallon. The thing is, I could never get the HC to take in another 90G tank with Eco complete and top dressed gravel. Pretty much same water with a 4x54 watt Tek light on the 90G. The HC is growing with a 4x39 watt Current Nova T5 on the new 65 gallon. So its not just the wattage, though everyone thinks HC needs tons of light. I don't think its the light, but rather a rich substrate and stable/ mature water. I don't even dose this tank that much letting the fish and excess food take care of most of the NO3 and PO4. The water is around KH 5 and GH of 6-7 with pH of 6.5. I only dose K and traces and not too much of traces. I also dose calcium chloride and mg as the well water is near RO. It is not too heavily stocked either.


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## banderbe

Edward said:


> Thank you hoppycalif
> Not knowing the CO2 level worried me for some time. When everything was growing well I couldn't test it due to the KH being at zero. One dose of baking soda exposed the probable CO2 level of 10-15 ppm. This was enough under high light 6 Watts per gallon PC.
> 
> Here are the CO2 rates:
> 10 gall => 10 bubbles / min
> 50 gall => 50 bubbles / min
> 100 gall => 100 bubbles / min
> 
> I would like to add that tiny aeration is beneficial when fish is in the aquarium.
> 
> Thank you
> Edward


That's interesting, I bubble 180 bubbles / min into my little 29 gallon tank. No leaks either as I just use a limewood airstone and can pull the tubing and see the bubbles coming out of the tube into the water. Even when I was using a reactor I had to push that much CO2 in order to get the one point ph drop.


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## Edward

banderbe said:


> That's interesting, I bubble 180 bubbles / min into my little 29 gallon tank. No leaks either as I just use a limewood airstone and can pull the tubing and see the bubbles coming out of the tube into the water. Even when I was using a reactor I had to push that much CO2 in order to get the one point ph drop.


What was your KH?


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## hoppycalif

I have found that having a good surface current, where the duckweed and bits of leaves move around at a very noticeable rate, requires a lot more bbs of CO2 to maintain the CO2 at the level I wanted. But, CO2 isn't expensive, so it doesn't bother me - I too use around 3-4 bbs of CO2 in a 29 gallon tank.


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## fresh_newby

I am interested in this theory, and testing it as well. I am about 9 weeks into a new 90 gal tank. The kH out of my tap is generally around 1, so I was using Bicarb to adjust then kept my pH controller at around 6.5-6.7 for a 28 ish CO2. This time I did not add the bicarb, so my kH is very low. My pH is now at 5.8, and I have the controller set at about 6.5, so it has been a day and a half since my CO2 even turned on! The pH has linearly drifted since my water change the other night from 6.7 to 5.8. I assume this is what many people refer to as a 'pH crash'. The chemistry doesn't make sense that it would truly crash; however. I am waiting to see if it plateaus. My fauna, corys, otos, rainbows, shrimp, Nerites, SAE, neons and swordtails, are all busy doing their thing and do not look at all stressed. yes even my Amanos are active. I am about to do a 30% water change just to see what it does. I am having issued with Eco complete andPO4 so I am down to 2 x's a week changes 30-50%. Anyway, will keep you posted. By the way, this is my first post :biggrin: :biggrin:


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## AaronT

fresh_newby said:


> I am interested in this thoery, and testing it as well. I am about 9 weeks into a new 90 gal tank. The kH out of my tap is generally around 1, so I was using Bicarb to adjust then kept my pH controller at around 6.5-6.7 for a 28 ish CO2. This time I did not add the bicarb, so my kH is very low. My pH is now at 5.8, and I have the controller set at about 6.5, so it has been a day and a half since my CO2 even turned on! The pH has linearly drifted since my water change the other night from 6.7 to 5.8. I assume this is what many people refer to as a 'pH crash'. The chemistry doesn't make sense that it would truly crash; however. I am waiting to see if it plateaus. My fauna, corys, otos, rainbows, shrimp, Nerites, SAE, neons and swordtails, are all busy doing their thing and do not look at all stressed. yes even my Amanos are active. I am about to do a 30% water change just to see what it does. I am having issued with Eco complete andPO4 so I am down to 2 x's a week changes 30-50%. Anyway, will keep you posted. By the way, this is my first post :biggrin: :biggrin:


You may want to disconnect the pH controller for the expirement as the CO2 will likely not ever turn on. Do you have a bubble counter? If so I would start with 1/2 to 1 bubble per second and see how the plants and fish do.

I'm glad to see you made it over to APC as well. Keep us updated on your progress.


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## Brilliant

I have been running like this since day one (which is like 4-6 months ago, so I am no expert). I had someone tell me my pH was going to crash and I got all worried and added baking soda....thats all over with...but now I feel much better not adding baking soda. I added some crushed coral for added calcium...mainly for my snails..from what I read it also keeps pH a little more stable.

My co2 worked out to be exactly whats stated in this post. I dont run an air stone.

Seeing this thread makes me feel much better. I joined up and hope to learn alot from this forum. I dont really have much to contribute except...thank you!


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## fresh_newby

Thanks AaronT  

OK well nothing was adding up! I did the water change, and my pH was stil 5.8. I knew something was off. I pulled out the pH probe, and hmmmm it was a point off! I recalibrated and am now at 6.6 with the CO2 going in 5/sec. YAY so my kH is at about 1-2 and I am back on track. Let this be a lesson...lol If the chemistry isn't making rational sense, and if the numbers are not what you would expect, always suspect the measuring device, beit a pH probe or a test kit. Question everything!


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## fresh_newby

and Brilliant...you are doing fine. If the plants and the fauna are happy and healthy, that is your validation. I am questioning everything right now because I am leery of my Eco/PO4 issue, so the last thing I want to do is be light on CO2.


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## Laith

fresh_newby said:


> ... Let this be a lesson...lol If the chemistry isn't making rational sense, and if the numbers are not what you would expect, always suspect the measuring device, beit a pH probe or a test kit. Question everything!


Definitely. If you're going to use test kits, calibrate them (test them against a known solution).

Also be aware that electrical interference can affect a pH probe's reading. On one tank if I turn off the lights my pH meter changes readings. On another tank turning off the lights makes no difference... So it's good to double check.


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## banderbe

Edward said:


> What was your KH?


My KH used to be 18.. now it's 3.

Either way I had to put the same 3 bubbles / second into the tank.


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## Edward

banderbe said:


> That's interesting, I bubble 180 bubbles / min into my little 29 gallon tank. Even when I was using a reactor I had to push that much CO2 in order to get the one point ph drop.





banderbe said:


> My KH used to be 18.. now it's 3.
> 
> Either way I had to put the same 3 bubbles / second into the tank.


This could be another prove that the widespread KH/pH/CO2 tables are not correct. In your case achieving the same one pH drop required the same amount of CO2 even though the KH was 3 and 18. According to the tables the CO2 level in the 18 KH aquarium should be 6x higher. It doesn't make sense, does it?

Thank you
Edward


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## ianiwane

I do 5bps into a 50 gallon tank kH is anywhere from 2-4 depends on the water out of the tap on any given day. Using an external reacter with no loss of co2.


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## Robert Hudson

> I do 5bps into a 50 gallon tank kH is anywhere from 2-4 depends on the water out of the tap on any given day. Using an external reacter with no loss of co2.


One question, how can you even count five bubbles per second? Anything more than 1 bubble per second just looks like a steady stream to me. Its too fast too much for me to come close to counting accurately


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## hoppycalif

Robert Hudson said:


> One question, how can you even count five bubbles per second? Anything more than 1 bubble per second just looks like a steady stream to me. Its too fast too much for me to come close to counting accurately


I find two bubbles per second pretty easy to count, but above that it is just an estimate. I consider mine to be 3+ bbs, but, for all I can tell, it could be 5. Since my bubbles go thru a powerhead pump I can hear each bubble hit the rotor, so that is pretty easy to count, or at least to compare to what it was yesterday.


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## Glouglou

*Low Ph = problem or not?*

Well, many scientific paper are out there on the net about low pH and the effect on life.

One that bother me is this one precising PH in relation with Nitrifying bacteria at Bio-Con Labs:

*Description of who they are:*


> About Bio-Con Labs, Inc.
> 
> Bio-Con Labs is aquaculture research and design facility located in Gainesville, Florida, USA. We have been in business since 1986, and specialize in providing total filtration solutions for aquatic systems containing live plants and animals.
> 
> Our primary customers are zoos, aquaculture facilities and research labs; but we enjoy working with people in other fields. If you are serious about solving your


http://www.bioconlabs.com/nitribactfacts.html



> pH
> 
> The optimum pH range for Nitrosomonas is between 7.8-8.0.
> 
> The optimum pH range for Nitrobacter is between 7.3-7.5
> 
> Nitrobacter will grow more slowly at the high pH levels typical of marine aquaria and preferred by African Rift Lake Cichlids. Initial high nitrite concentrations may exist. At pH levels below 7.0, Nitrosomonas will grow more slowly and increases in ammonia may become evident. Nitrosomonas growth is inhibited at a pH of 6.5. All nitrification is inhibited if the pH drops to 6.0 or less. Care must be taken to monitor ammonia if the pH begins to drop close to 6.5. At this pH almost all of the ammonia present in the water will be in the mildly toxic, ionized NH3+ state.


Don't look to good for me...:icon_hang


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## banderbe

Sounds like baloney to me Glouglou. I mean, at least in my experience.. my pH is easily in the mid to low 5's and I have no problem. Evolutionarily speaking it doesn't make sense either since there would have been ample opportunity for these bacteria to adapt to acidic solutions.


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## BryceM

First of all, in a planted tank, who cares about nitrifying bacteria? The plants take up so much that most of us have to add it back in.

I find this thread to be good food for thought. I'll throw in my random comments. First of all, it is essential to remember that one person's observations do not constitute scientific fact. I'm not aiming at anyone in particular by saying this and I don't want to sound argumentive, but it's important to remember. There are dozens of variables that aren't controlled for. I think Edward's approach of keeping fish in a KH of zero is interesting, and reveals that a lot of what we pass around as "fact" probably isn't.

Person X might like to keep 10 full-grown oscars in a 55 gallon tank while person Y has 2 endlers in a similar setup. One person's 4 watts per gallon is measured with old bulbs, no reflector, and a dirty cover while another uses brand-new AH-Supply stuff. One person's test kit says 7.4 while another's poorly calibrated probe says 6.2. Which is right? People in different areas have widely different tapwater. Fortunately, plants and fish are pretty adaptable and most everyone is able to find some approach that works. An understanding of the principles behind the physiology and chemistry is more important than trying to get parameter "X" to a certain value.

Regarding the KH/CO2/pH chart...... It works perfectly well as long as carbonic acid from CO2 is the only acid in the system and carbonates are the only buffers. Since this is never true, the chart can never be expected to be accurate. In almost every case it will overestimate the amount of CO2 present. Decomposition of fish food, fish waste, plant matter, driftwood, and other compounds will inevitably introduce organic acids that accumulate with time. Talking about ppm of CO2 is almost a useless exercize. I still think that dropping pH about 1.0 units from the degassed state is a pretty good way to get where you want to be. If you want to use a pH controller, thats perfectlyl fine, but you need to monitor the KH and degassed pH once in a while.

Regarding pearling...... This is a phenomenon that is observed when plants are producing O2 in water that is already O2 saturated. The best way to get pearling is a low fish load, tight fitting cover, intense lighting, perfect ferts, and a jungle of rapidly growing plants (stemmies). If you have a high fish load you might never see pearling. If you have only slowly metabolizing plants or a low plant density you might not overcome the rate of O2 loss to the atmosphere. Despite this, the plants can be perfectly healthy and growing quite well. If the plants aren't metabolizing due to a nutrient deficiency, no amount of CO2 will cause them to pearl.

I suspect that most of what gets reported around the internet as a "pH crash" is actually an ammonia spike. A low plant mass with an overstocked tank and a poorly functioning biofilter is a perfect setup. Nothing kills fish more quickly. A sudden increase in CO2 is also pretty impressive. I've seen this kill fish in a matter of minutes.

Being vertebrates, the biochemistry that takes place in a fish is pretty similar to our own. Hemoglobin is the carrier of oxygen in the blood stream and it looses its ability to carry oxygen when CO2 levels get too high. When humans experience a gradual increase in CO2 (such as in lung disease), blood pH goes down and our kidneys compensate by producing more bicarbonate and dumping more acid.The cellular mechanisms that compensate for high CO2 take hours or days to kick in and they're only effective to a certain point. Fish do the same thing, with much of their regulation taking place in their gills, as opposed to the kidney.

Cellular processes are also quite dependent on a stable pH inside the cell. Even a couple of tenths of a point can cause big problems. Fortunately the body has quite powerful mechanisms to regulate pH. I think Edward is right that high CO2 levels can be more toxic than low pH levels. For most people though, it's hard to understand the difference. This is probalby due to the fact that we're all accustomed to equating pH to CO2.

Still, there is a certain pH below which the fish can't adapt. This exact point differs between species. Fish that evolved in areas of low KH, like tetras and South American chiclids get along much better at lower pH levels than Rift Lake chiclids. It sounds perfectly reasonable to me that fish can survive in a pH of 3.7, although I'd recalibrate the probe once or twice to prove it. Just don't try to reproduce Edward's results without understanding how he got there. His water has no buffering capacity whatsoever. If you try to get to pH 3.7 by cranking up the CO2 you won't have to worry about the fish anymore.

Whew, what a novel....... sorry


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## hoppycalif

Yes, it was a novel, but a gripping page turner! I agree with everything you said, but reserve the right to change my mind tomorrow!


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## Skyfish

My tap Kh is 1 and I used to use bicarbonate to raise it to 4. Had a controller set at PH6.4. I knew what my Co2 was. This week I switched to ADA AS/PS and my Ph just dropped to 6.0 without adding Co2 and Kh was at 0. I am not using the controller anymore. I added bicarbonate and kH raised to 2.3 but at my 1st water change it was back to 0 and PH had dropped to 5.7. After a day back up again at 6.0. Now after reading this thread, I am not going to do add any buffer. Let it sit at 0. But my question is how do we know how much Co2 is present in the water column? With new/old plants in this new setup it will take a few weeks to stabalize. But I want to be rest assured that I have enough Co2 going in there. It's 75G, 3bps, dissolved through an inline Rex reactor. The Stellata and Umbrosum are showing signs of growth already.

Your findings are based on normal gravel with let's say peat base or not. But what about with ADA substrate where it brings everything down? Sorry if this is a dumb question.


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## hoppycalif

Skyfish said:


> My tap Kh is 1 and I used to use bicarbonate to raise it to 4. Had a controller set at PH6.4. I knew what my Co2 was. This week I switched to ADA AS/PS and my Ph just dropped to 6.0 without adding Co2 and Kh was at 0. I am not using the controller anymore. I added bicarbonate and kH raised to 2.3 but at my 1st water change it was back to 0 and PH had dropped to 5.7. After a day back up again at 6.0. Now after reading this thread, I am not going to do add any buffer. Let it sit at 0. But my question is how do we know how much Co2 is present in the water column? With new/old plants in this new setup it will take a few weeks to stabalize. But I want to be rest assured that I have enough Co2 going in there. It's 75G, 3bps, dissolved through an inline Rex reactor. The Stellata and Umbrosum are showing signs of growth already.
> 
> Your findings are based on normal gravel with let's say peat base or not. But what about with ADA substrate where it brings everything down? Sorry if this is a dumb question.


If you use the same reactor and the same bubble rate you should have very near the same amount of CO2 dissolved in the water. From there you can watch to see if BBA starts sprouting up - if it does you need more CO2. You can watch the fish to see if they seem distressed - if so you may be too high on CO2. And, you can watch the plants to see how well they grow, how much pearling they do, and from that decide if you need more CO2. There really isn't any accurate way to actually measure how much CO2 is in the water without spending a lot of money for much more sophisticated testing equipment. And, since our standard of 20-30 ppm CO2 is based on people's inaccurate measurements we can't even say what the optimum real CO2 concentration is.


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## Skyfish

hoppycalif said:


> If you use the same reactor and the same bubble rate you should have very near the same amount of CO2 dissolved in the water. From there you can watch to see if BBA starts sprouting up - if it does you need more CO2. You can watch the fish to see if they seem distressed - if so you may be too high on CO2. And, you can watch the plants to see how well they grow, how much pearling they do, and from that decide if you need more CO2. There really isn't any accurate way to actually measure how much CO2 is in the water without spending a lot of money for much more sophisticated testing equipment. And, since our standard of 20-30 ppm CO2 is based on people's inaccurate measurements we can't even say what the optimum real CO2 concentration is.


Thanks hoppy. In a new setup with AS and PS you can't add fish for at least 4 weeks, so we'll have to rely on plant pearling/growth. Today after my 5th day, I have seen bubbles behind all my Java Fern and Bolbitus, and some tiny bubbles going upwards from some of the plants, so I think the CO2 is doing well. But I have not seen a drop in PH during the day due to CO2. KH remains less then 1.


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## hoppycalif

As long as there are no fish or shrimp in the tank you can raise the CO2 amount as high as you want, just to see what effect it has, or to try to zero in on the bubble rate that gives maximum benefits. Since you have to wait to add fish, why not use the time to experiment? It won't harm the plants.


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## Skyfish

hoppycalif said:


> As long as there are no fish or shrimp in the tank you can raise the CO2 amount as high as you want, just to see what effect it has, or to try to zero in on the bubble rate that gives maximum benefits. Since you have to wait to add fish, why not use the time to experiment? It won't harm the plants.


Thank you Hoppy. My current bubble rate is 3bps and I did see bubbles forming behind the java fern and bolbitus, but I have cranked it up now, I can't tell how many as it is pretty fast, let's see what happens. Next week I will be adding shrimps and Ottos, so till then I can play around with it. I do however switch off the CO2 at night, should I leave it on 24/7? BTW the KH is still below 1ppm.


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## hoppycalif

Skyfish said:


> Thank you Hoppy. My current bubble rate is 3bps and I did see bubbles forming behind the java fern and bolbitus, but I have cranked it up now, I can't tell how many as it is pretty fast, let's see what happens. Next week I will be adding shrimps and Ottos, so till then I can play around with it. I do however switch off the CO2 at night, should I leave it on 24/7? BTW the KH is still below 1ppm.


If you don't have any fish or shrimp it doesn't make any difference whether or not you shut off the CO2 at night, other than the CO2 usage, and the time to reach maximum CO2 in the water each morning. I think the goal of this exercise is to teach you what the tank looks like when you are absolutely sure you have plenty of CO2 in it. That makes it much easier to recognize when you don't.


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## ruki

guaiac_boy said:


> First of all, in a planted tank, who cares about nitrifying bacteria? The plants take up so much that most of us have to add it back in.


With billions of such bacteria, I think this is another blow the assumption that C02/carbonic acid/pH is an isolated, independent system behind the pH change dissolved CO2 chart. Secondary changes will be going on at least in the background because a large biosystem has been throttled back by a pH change. We could really use an inexpensive way to directly measure the dissolved C02 to know what is going on.



> I think Edward's approach of keeping fish in a KH of zero is interesting, and reveals that a lot of what we pass around as "fact" probably isn't.


Humans recognise patterns, whether valid or not. Perhaps I could become rich starting up an aquatic plant religion where people started noticing good things happen when they send me donations to construct a temple to a yet-to-be-defined diety. 



> An understanding of the principles behind the physiology and chemistry is more important than trying to get parameter "X" to a certain value.


But that's not how most people "learn". It's easier to have a religious faith based upon pH crash killing fish, when it could be something else (i.e. pH was actually lower, but it was an effect not the cause of the fish deaths.) They saw dead fish, lower pH, therefore confirmation!



> Regarding the KH/CO2/pH chart...... It works perfectly well as long as carbonic acid from CO2 is the only acid in the system and carbonates are the only buffers. Since this is never true, the chart can never be expected to be accurate.


This is conceptally nasty because hardnes and the resulting equilibrium states between a buffer and the dissolved ion/acids of the mineral plus the interaction between free H and free OH and is conceptually quite difficult.


> Decomposition of fish food, fish waste, plant matter, driftwood, and other compounds will inevitably introduce organic acids that accumulate with time.


And other stuff in the aquarium which dissolves much more readily when pH drops. You can and probably do have significantly more dissolved "crud" in the water if you drop the pH from 6.5 to 5.5. That could also be a factor in the 'pH crash' fish deaths.



> I suspect that most of what gets reported around the internet as a "pH crash" is actually an ammonia spike. A low plant mass with an overstocked tank and a poorly functioning biofilter is a perfect setup. Nothing kills fish more quickly. A sudden increase in CO2 is also pretty impressive. I've seen this kill fish in a matter of minutes.


That might be. By the time one gets to measuring this with test kits, the ammonia spike may have gone away since the system can handle a certain base rate which will absorb temporay spikes. People notice the next day they have dead fish, but their ammonia and nitrates test out at zero.



> Being vertebrates, the biochemistry that takes place in a fish is pretty similar to our own. Hemoglobin is the carrier of oxygen in the blood stream and it looses its ability to carry oxygen when CO2 levels get too high.


Because hemoglobin can't dump CO2 into the air when the air is already nearly saturated with CO2. The same thing can happen to fish. In this way, too much CO2 can directly kill fish via a fairly simple to understand mechanism.



> When humans experience a gradual increase in CO2 (such as in lung disease), blood pH goes down and our kidneys compensate by producing more bicarbonate and dumping more acid.


Don't think the kidneys can produce bicarbonate. Other functions in the body will dissolve bone if neccesary to keep pH from getting too low.



> I think Edward is right that high CO2 levels can be more toxic than low pH levels. For most people though, it's hard to understand the difference. This is probalby due to the fact that we're all accustomed to equating pH to CO2.


Because most people don't have a science background, so they stuck memorizing religious type rules such delta pH change equals dissolved CO2. The biggest problem is that people don't understand that this is an estimator with a +/- error range since this is never included in the charts to make them easier to understand. How can one calibrate this? Without such calibration, we don't understand the margin of approximation (i.e. error) in what we read off the chart.



> Still, there is a certain pH below which the fish can't adapt. This exact point differs between species.


Even this is a nasty experiment. In your tank you could have something that dissolves in the water only at a very low pH and that is what really killed the fish, even though you can only measure that the fish started dieing off at pH 5.3. You would need a bare tank with just fish and multiple acids in different tanks to see if a common low pH killed the fish.[/quote]



> Whew, what a novel....... sorry


One needs a novel to resolve each sub question!


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## BryceM

Wow ruki, quite a lenghty response. One of the primary reasons that I enjoy planted tanks is that there is ample subject material for thought. It's nice to stretch one's brain once in a while. It's probably pretty obvious to most people on this board that I sometimes stretch mine a bit too far, hehe.

I am wondering about what you mean by this statement though:



ruki said:


> Don't think the kidneys can produce bicarbonate. Other functions in the body will dissolve bone if neccesary to keep pH from getting too low.


Maintainence of blood bicarbonate is a primary function of the kidney/gill. It might be more correct to state that they regulate readsorption vs excretion, but for all practical purposes it results in the same thing - more bicarbonate in the blood.

As far as I know, skeletal catabolism isn't a primary mechanism for pH control. Osteoclasts will increase their adsorption of bone as a result of many stimuli, but most often this is in response to serum calcium levels, phosphate levels, or various endocrine disorders.

Sorry to get so far off-topic. Your point about other potentially toxic substances dissolving more readily at low pH levels is a good one. In at least one area though, low pH levels can be protective. Ammonia toxicity will be almost impossible at a pH as low as Edward is talking about since it will virtually all be converted immediately to ammonium.


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## Glouglou

*About Baloney!*

To respond to my message about problems caused by low PH on Nitrifying bacteria.

Coming from *US Environment Protection Agency*

A very interesting paper (PDF 15 pages) on *Nitrification*

http://www.epa.gov/safewater/tcr/pdf/nitrification.pdf

I quote:


> nitrifying bacteria are very sensitive to pH as shown in Figure 3. Nitrosomonas has an optimal pH between approximately 7.0 and 8.0, and the optimum pH range for Nitrobacter is approximately 7.5 to 8.0. Some utilities have reported that an increase in pH (to greater than 9)


and 2 other interessant point on the consomation of bicarbonates in amonia-nitrogen oxidation and the final effect of low KH on PH stability.
I quote:


> A model developed by Gujer and Jenkins (1974) indicates that 8.64 mg/L of bicarbonate (HCO3-) will be utilized for each mg/L of ammonia-nitrogen oxidized. Reductions in alkalinity can cause reductions in buffering capacity, which can impact pH stability.


I don't know if all the paper on the subject of lower KH that destabilize PH are baloney but they are very clear to me.
eace:

*Even with all the nice theory out there, putting your hand in fire will always burn.*:mad2:


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## BryceM

Glouglou,

Yes, exactly! As ammonia is taken through the nitrogen cycle, acid is produced. It's basic proton chemistry. If you start with NH3 and end up with NO3- those protons went somewhere. To greatly simplify, they end up in solution as acid and this "consumes" some of the available bicarbonate. What you see is a pH drop. This makes up part of the "organic acid" that I refer to when stating that the pH/CO2/KH chart doesn't work very well.


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## ruki

guaiac_boy said:


> I am wondering about what you mean by this statement though:
> 
> 
> 
> 
> Originally Posted by ruki
> Don't think the kidneys can produce bicarbonate. Other functions in the body will dissolve bone if neccesary to keep pH from getting too low.
> 
> 
> 
> Maintainence of blood bicarbonate is a primary function of the kidney/gill. It might be more correct to state that they regulate readsorption vs excretion, but for all practical purposes it results in the same thing - more bicarbonate in the blood.
Click to expand...

I was taking the absolutist position that the kidneys regulate pH by choosing to dump or not dump something. They don't produce it, it's initially absorbed by the intestines. They get it from the blood and choose to release it or not. They can store it in intermediate forms to supply buffering capacity, but there is a limit to how much can be stored in the buffer.



> As far as I know, skeletal catabolism isn't a primary mechanism for pH control. Osteoclasts will increase their adsorption of bone as a result of many stimuli, but most often this is in response to serum calcium levels, phosphate levels, or various endocrine disorders.


I'm not a medical person, but may have read too many articles which sometimes are oversimplifed to the point of being misleading. One of the frequently repeated health tips for osteoporosis is to not drink carbonated beverages since this will try to raise the pH of the body. If you do not consume enough high pH items, the body will dissolve bone to maintain equilibrium. The kidneys can not produce enough bicarbonate if you don't consume enough base materials and instead consume lots of carbonated beverages. Is this accurate or inaccurate?


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## BryceM

Boy, we're really off-topic here. I think I might pull this whole section out and start a new thread in the waterbucket to clean up the original thread.

The issue with carbonated beverages is that most of them contain huge quantities of phosphates in the form of phosphoric acid. Calcium regulation in the body is closely tied to serum phosphate levels. When phosphate levels are high (such as in renal failure or excessive soda pop consumption), the body tries to get rid of calcium. Uptake of calcium from the intestine is also slowed down.

To see clinical long-term effects such as osteoporosis you'd need to drink colossal quantities of soda over a period of many years, but that certainly doesn't exclude many people here in the US.

With regards to bicarbonate, it's a pretty simple molecule and the body has many enzymatic mechanisms for producing it and breaking it down in various locations. It isn't transported across the lumen of the glomerulus or the lumen of the gut in its native form. The actual transport occurs as CO2. A little acid-base aqueous chemistry, mediated by enzymes, and presto......., for all intents and purposes, HCO3- is produced. The enzyme carbonic anhydrase (also present in plants, allowing them to extract carbon directly from carbonate) is involved in this process.


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## ruki

I once spoke with a co-worker who had a kidney stone. He refused to give up the soda though. So, the dumping of Calcium gets done via the kidneys and has little to nothing to do with the carbonate used to balance body pH?


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