CO2 chart

[Mebbid]

I am going to be adding a fairly tightly fitting glass lid onto my pico tank here as soon as the clips come in and I was trying to figure out a way to determine the level of CO2 in the water. The first thing that came to mind was a co2 chart that planted tank keepers use to judge their addition of c02 but it bases everything off of just kH and pH. I wasn't sure if it would apply to salt water as well because I'm not sure what other pH buffers there are in salt other than just the kH. So do you guys think this would carry over to salt was well?

 

[Delapool]

Hi, did you come up with anything? I couldn't think of anything off the top of my head but SW isn't my field.

 

[Caliban07]

I am going to be adding a fairly tightly fitting glass lid onto my pico tank here as soon as the clips come in and I was trying to figure out a way to determine the level of CO2 in the water. The first thing that came to mind was a co2 chart that planted tank keepers use to judge their addition of c02 but it bases everything off of just kH and pH. I wasn't sure if it would apply to salt water as well because I'm not sure what other pH buffers there are in salt other than just the kH. So do you guys think this would carry over to salt was well?

I'm not sure how accurate this chart is tbh. I suppose it better than nothing and can only be classed as an estimate or indicator.

From wiki

"In a solution where only CO2 affects the pH, carbonate hardness can be used to calculate the concentration of dissolved CO2 in the solution with the formula CO2 = 3 * KH * 10(7-pH), where KH is degrees of carbonate hardness and CO2 is given in ppm"

Who knows what is affecting ph in our aquariums with the amount of stuff we add/do.

Even then you have to rely on the accuracy of the kh tester.

Perhaps something like this would be better but I bet it costs a bomb

http://www.hach.com/carbon-dioxide-test-kit-model-ca-23/product?id=7640218474


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[Caliban07]

I think it can be used for saltwater too. There is an option to chat to a representative during open hours.

I'll bet they would be willing to answer some questions. Might be a refreshing change for them not having to answer a question for an industrial point of view.


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[Mebbid]

I haven't found anything on it sadly. I do have a nice kh test kit though, I use red sea for the important tests.

Wish I had disposable income for something like that test kit.

I was also thinking, maybe I could use a drop checker. It shouldnt be affected at all by any buffering of the salt water.

 

[Delapool]

I think it can be used for saltwater too. There is an option to chat to a representative during open hours.

I'll bet they would be willing to answer some questions. Might be a refreshing change for them not having to answer a question for an industrial point of view.


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How much was it?

 

[Caliban07]

How much was it?

You have to contact them for a price


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[Caliban07]

I haven't found anything on it sadly. I do have a nice kh test kit though, I use red sea for the important tests.

Wish I had disposable income for something like that test kit.

I was also thinking, maybe I could use a drop checker. It shouldnt be affected at all by any buffering of the salt water.

I don't think alkalinity is the thing that distorts the accuracy of the calculation.

I'm only guessing at this point but the equations takes kh in to consideration regardless of what the level is. As the only other thing required to calculate co2 is ph I think it is the other acids/bases in the water that effect ph that makes it difficult to calculate. In order to get a true representation if co2, you would have to be certain that co2 was the only determining factor of ph.

So it would seem that this chart is accurate because it is assuming that the specified ph level is co2 dependent which makes the calculation relevant however that is simply not true in our tanks because of the unknown variables that may be contributing to the ph level.

My understanding could be wrong though.


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[Mebbid]

I don't think alkalinity is the thing that distorts the accuracy of the calculation.

I'm only guessing at this point but the equations takes kh in to consideration regardless of what the level is. As the only other thing required to calculate co2 is ph I think it is the other acids/bases in the water that effect ph that makes it difficult to calculate. In order to get a true representation if co2, you would have to be certain that co2 was the only determining factor of ph.

So it would seem that this chart is accurate because it is assuming that the specified ph level is co2 dependent which makes the calculation relevant however that is simply not true in our tanks because of the unknown variables that may be contributing to the ph level.

My understanding could be wrong though.


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Good summarization and you hit the nail on the head

My main curiosity behind this chart is whether or not there are other factors influencing the pH in the tank. I don't believe there is, but water chemistry still isn't one of my strong points.

 

[Caliban07]

Good summarization and you hit the nail on the head



My main curiosity behind this chart is whether or not there are other factors influencing the pH in the tank. I don't believe there is, but water chemistry still isn't one of my strong points.

It's difficult to say. I suppose ph fluctuations would be common if the things we added/removed from the water column mattered.

I would go with the chart as I believe it's the best thing we got to go with at the moment


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[Caliban07]

My main concern is the level of certainty which brings us back to the original post lol. Just needed to make sure I understood the question.


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[Mebbid]

My main concern is the level of certainty which brings us back to the original post lol. Just needed to make sure I understood the question.


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I'm thinking at this point it's more effective to just use a drop checker which would negate anything related to buffering in the tank. At this point I just need to know a number for co2 to be at so I can make a reference solution to match

 

[Caliban07]

Sounds like a bit of a faff. Better to be safe than sorry though. What is the co2 for in marine setup?


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[Mebbid]

Sounds like a bit of a faff. Better to be safe than sorry though. What is the co2 for in marine setup?


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I am adding a fairly tight fitting lid on my pico tank mainly to keep the salt water from splashing on the DIY fixture I am going to be adding in. Secondarily to cut down on evaporation. I want to monitor the co2 levels to make sure I am not going to suffocate any of the livestock.

 

[Caliban07]

I am adding a fairly tight fitting lid on my pico tank mainly to keep the salt water from splashing on the DIY fixture I am going to be adding in. Secondarily to cut down on evaporation. I want to monitor the co2 levels to make sure I am not going to suffocate any of the livestock.

Can you not clip on a fine mesh that would stop splashing and still allow gas to pass through. I'm sure you could make something sturdy?


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[Caliban07]

http://www.simplyaquaria.co.uk/diy-tank-cover.html


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[Mebbid]

Can you not clip on a fine mesh that would stop splashing and still allow gas to pass through. I'm sure you could make something sturdy?


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If it were fresh water I wouldn't worry about it as much but the salt is soo corrosive. The nature of the cover of the aquarium makes it so I can't really cover the LEDs with anything. Also, with the air being dry the tank is evaporating soo much water that in the matter of 12 - 24 hours or so the water is approaching the minimum level for the tank to still function.

 

[Caliban07]

If it were fresh water I wouldn't worry about it as much but the salt is soo corrosive. The nature of the cover of the aquarium makes it so I can't really cover the LEDs with anything. Also, with the air being dry the tank is evaporating soo much water that in the matter of 12 - 24 hours or so the water is approaching the minimum level for the tank to still function.

That's insane! Drip counter it is then.


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[Delapool]

I've found that a phosphate buffer is throwing off the calculation (it seems). Also other acids from driftwood can throw it out. I'd assume for SW these wouldn't be a problem?

I've read some arguments on other forums that said the chart was +/- 20% accuracy. Unfortunately didn't keep the link as had a stiff drink after reading through it.

 

[jeffaquarius]

Testing CO2 in salt water tank is not recommended. Your readings will be meaningless since pH level is in the higher level than planted fresh water tank.