pH, gH, kH and Co2 - The Planted Tank Forum
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post #1 of 5 (permalink) Old 10-24-2005, 10:33 PM Thread Starter
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pH, gH, kH and Co2

Is there a formula you can use to determine your CO2 levels using your test results for pH, gH, and kH? I tried to download the CO2 chart above, thinking it might hold the answer, but I couldn't open the file.

Right now I have low light, virtually no additional CO2 (just Excel) and very, very hard water (gH 240, kH 150-160, pH 8.4-8.6).

Over the next month I will be almost quadrupling my light and adding compressed CO2 , but in the meantime, just wondering...
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post #2 of 5 (permalink) Old 10-24-2005, 10:36 PM
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post #3 of 5 (permalink) Old 10-25-2005, 01:09 AM
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160 ppm x 0.056 = 8.96 °dH (the chart uses °dH for KH)

so according to Rex Grigg's chart you have less than 1.0 ppm of CO2, but that's not counting the Excel.
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post #4 of 5 (permalink) Old 10-25-2005, 07:38 AM
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Originally Posted by choppy
...very, very hard water (gH 240, kH 150-160, pH 8.4-8.6).
Very hard water? *That's* not very hard water!

*This* is very hard water (my tap and tank water): GH of 18 (320ppm), KH of 15 (270ppm)!
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post #5 of 5 (permalink) Old 10-25-2005, 08:04 AM
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CO2 (in PPM) = 3 * KH * 10( 7-pH ) where KH is Carbonate Hardness in degrees

This page has the formula, a webpage calculator and the chart.

It helped me a lot when I was figuring this stuff out.

"Insanity: doing [or asking] the same thing over and over again and expecting different results."
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