The Planted Tank Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
588 Posts
I'm not a chemist but I'm almost 100% sure a sodium-hydroxide titation will not produce an accurate reading of carbonic acid if there are any other buffers in solution.

I'd also be skeptical of any system that requires you swirl or shake the sample. After swirling the mixture thirty times I don't think much of the original CO2 will remain.

• Collect samples in clean glass or plastic bottles with tight-fitting caps. Completely fill
the bottle and immediately tighten the cap.
• Prevent agitation of the sample and exposure to air.
• Analyze the samples as soon as possible for best results

A phenolphthalein indicator is added to the sample. Carbonic acid formed by carbon
dioxide in the sample is titrated with a sodium hydroxide standard solution until the
indicator changes color at the endpoint pH of 8.3. Strong acids cannot be in the sample at
concentration levels that will have an effect on the results.
 

·
Registered
Joined
·
1,916 Posts
A lot of people seem to be looking for something like this lately. I still dont understand why? What are you going to do once you have an actual "number" ? Is it just for bragging purposes of some sort? I've been running pressurized co2 for about a year now and never once have I cared to know exactly how much co2 is in any one of my tanks. And even if I did I'm not sure what I would do with that information.

The beauty of co2 in my eyes is that its one of the few things you can do to an aquarium and see a potential result quickly. Add too much and your fish will almost instantly tell you. I suppose you may add too little at the beginning; but its not all too hard to adjust as needed. Thats why experienced users will recommend to newbies that they adjust the co2 and closely monitor the fish. Crank it up slowly till the fish show a negative reaction and then back it off a bit.
 
  • Like
Reactions: benealing

·
Registered
Joined
·
21,012 Posts
When I first started using CO2 I did the monitoring of the fish, etc. and every time a fish looked at me I was sure I was distressing it. (Possible, from what I see in my mirror). So, I was running a pretty low bubble rate. Then I started using a drop checker, and found out that I had barely more than atmospheric CO2 in the water. Once I got the drop checker to become green I noticed the fish were acting just like they did before I added it. Later, mostly because of problems with the regulator, I did cause distress, including killing some fish, but that's another story. So, I continue to recommend buying a cheap drop checker, on Ebay or elsewhere, making or buying some 4 dKH standard water, adding that and 2 drops of API pH reagent to the drop checker bubble, and using that to give yourself the confidence to raise the CO2 bubble rate high enough to get a significant amount of CO2 in the water. Once you get it green you can then work on finding the optimum bubble rate to use.

Bump:
I'm not a chemist but I'm almost 100% sure a sodium-hydroxide titation will not produce an accurate reading of carbonic acid if there are any other buffers in solution.

I'd also be skeptical of any system that requires you swirl or shake the sample. After swirling the mixture thirty times I don't think much of the original CO2 will remain.
I noticed that this is aimed primarily at people who monitor the CO2 in natural occurring water bodies, not at planted tank hobbyists. I'm not sure if this titration method is as iffy as the KH/pH table method, but I can see how it could be. I'm also not a chemist.
 

·
Premium Member
Joined
·
606 Posts
A question that just occurred to me:

Does the number of drop of pH reagent affect the accuracy of the test? I use the 4dKh solution, but find I have a harder time reading me drop checker unless there is 4-6 of the pH reagent in there.

Not really of significance because my plants are growing like weeds and the fish don't care at all. More for academic reasons than anything else.

Ben
 

·
Registered
Joined
·
114 Posts
Discussion Starter · #6 ·
When I first started using CO2 I did the monitoring of the fish, etc. and every time a fish looked at me I was sure I was distressing it. (Possible, from what I see in my mirror). So, I was running a pretty low bubble rate. Then I started using a drop checker, and found out that I had barely more than atmospheric CO2 in the water. Once I got the drop checker to become green I noticed the fish were acting just like they did before I added it. Later, mostly because of problems with the regulator, I did cause distress, including killing some fish, but that's another story. So, I continue to recommend buying a cheap drop checker, on Ebay or elsewhere, making or buying some 4 dKH standard water, adding that and 2 drops of API pH reagent to the drop checker bubble, and using that to give yourself the confidence to raise the CO2 bubble rate high enough to get a significant amount of CO2 in the water. Once you get it green you can then work on finding the optimum bubble rate to use.
I'm using a drop checker in conjunction with a pH meter. But the two don't seem to match up. Normally people say you need a 1 pH drop to have 30 ppm CO2, correct? But I guess I'm unclear if this is a 1 drop as measured from straight out of the tank or one from tank water and set aside and allowed to degas? I'm now going over a 1 pH drop compared to completely degassed tank water, but the drop checker is a solid green... Not even what I'd call a lime green. So I saw this and was curious if it could give me a better idea of what is going on.
 

·
Registered
Joined
·
975 Posts
When I first started using CO2 I did the monitoring of the fish, etc. and every time a fish looked at me I was sure I was distressing it. (Possible, from what I see in my mirror). So, I was running a pretty low bubble rate. Then I started using a drop checker, and found out that I had barely more than atmospheric CO2 in the water. Once I got the drop checker to become green I noticed the fish were acting just like they did before I added it. Later, mostly because of problems with the regulator, I did cause distress, including killing some fish, but that's another story. So, I continue to recommend buying a cheap drop checker, on Ebay or elsewhere, making or buying some 4 dKH standard water, adding that and 2 drops of API pH reagent to the drop checker bubble, and using that to give yourself the confidence to raise the CO2 bubble rate high enough to get a significant amount of CO2 in the water. Once you get it green you can then work on finding the optimum bubble rate to use.
I'm using a drop checker in conjunction with a pH meter. But the two don't seem to match up. Normally people say you need a 1 pH drop to have 30 ppm CO2, correct? But I guess I'm unclear if this is a 1 drop as measured from straight out of the tank or one from tank water and set aside and allowed to degas? I'm now going over a 1 pH drop compared to completely degassed tank water, but the drop checker is a solid green... Not even what I'd call a lime green. So I saw this and was curious if it could give me a better idea of what is going on.
Yes. What your talking about is in comparison to degassed tank water or tank water with only atmospheric concentrations of co2.


A lot of people seem to be looking for something like this lately. I still dont understand why? What are you going to do once you have an actual "number" ? Is it just for bragging purposes of some sort? I've been running pressurized co2 for about a year now and never once have I cared to know exactly how much co2 is in any one of my tanks. And even if I did I'm not sure what I would do with that information.

The beauty of co2 in my eyes is that its one of the few things you can do to an aquarium and see a potential result quickly. Add too much and your fish will almost instantly tell you. I suppose you may add too little at the beginning; but its not all too hard to adjust as needed. Thats why experienced users will recommend to newbies that they adjust the co2 and closely monitor the fish. Crank it up slowly till the fish show a negative reaction and then back it off a bit.
I recently asked a question like this and yeah heck yeah purely academic. Fun though. Just because it doesn't have an immediate application doesn't mean it's not fun to read about or know. To me anyway
 

·
Registered
Joined
·
114 Posts
Discussion Starter · #8 ·
Yes. What your talking about is in comparison to degassed tank water or tank water with only atmospheric concentrations of co2.
OK, thanks. I'm going to degas some more tank water and check it again. It's been a while since I've done that and maybe something has changed. Also, I think I'm going to try this kit out. It may prove worthless, but now I'm curious. I'll post an update with what I find.
 

·
Registered
Joined
·
975 Posts
Yes. What your talking about is in comparison to degassed tank water or tank water with only atmospheric concentrations of co2.
OK, thanks. I'm going to degas some more tank water and check it again. It's been a while since I've done that and maybe something has changed. Also, I think I'm going to try this kit out. It may prove worthless, but now I'm curious. I'll post an update with what I find.
Yes please do.
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top