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Originally Posted by Bert H  Perhaps I am being a little dense here, but aren't you still measuring the pH? You still have all the factors which affect the accuracy/inaccuracy of this methodology. So you will have a ball park figure with it. Isn't that what you have now just by measuring pH? |
You would be measuring a single pH and not two pH's and subtracting them, which can double the error in their measurement. The downside would be that the color of the reagent would be harder to see, since it would be much farther from the color comparison chart. Also, the water whose pH you would be measuring would have a known KH, with no other sources of alkalinity or acidity except the CO2, which would be the same ppm (?) as in the tank water. So, this should give a much more accurate indication of how much CO2 you have, without running into one of those cases where your KH/pH say you have 100 ppm CO2 but the fish are perfectly happy. My chemistry knowledge is skimpy, so I am just assuming that these indicators work because the water in the indicator reaches an equillibrium with the tank water so both have the same ppm of CO2. In any case, I have ordered the ebay version of the "drop checker" and will do some experimenting when I get it.