The Planted Tank Forum - View Single Post - Affordable CO2 sensor?
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Old 11-04-2012, 07:42 PM   #15
Darkblade48
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Quote:
Originally Posted by Hoppy View Post
But, 30 ppm of CO2 dissolved in water isn't in equilibrium with 30 ppm of CO2 in air. My education is lacking in this field, so I have no idea how to even start to solve this.

Air can have a varying amount of CO2 in it. If it is .03% CO2, it is 300 ppm, but water exposed to that air will contain more like 3 ppm of CO2. If the ppm in the water in equilibrium with the air above the water is a near constant percentage of the ppm in the air, this is an easy problem, but Murphy's Law seems to dictate that it isn't anywhere near a constant percentage.
So it is an issue with the rate of diffusion, but also the solubility of CO2 in the water?

I'm a microbiologist, not a chemist (though I have a minor, haha). Perhaps we need to get a chemist on this

Quote:
Originally Posted by mistergreen View Post
Same reason not to to use tank water in a drop checker. The ph will be affected by other things besides co2 throughout the day like rocks, substrate, driftwood. We're not dealing with an empty tank of water.
Aha, I don't know why I missed this.
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