<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by 2la:
If you're injecting CO2 at a certain level into a non-peat-filtered tank, wouldn't you have the same CO2 concentration if you just added peat to the filter's media chamber--just at a lower pH? Or am I taking too simple a view of this? http://www.picturetrail.com/2la
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Nope. That's all there is to it. Adding peat changes both KH and pH, but it has no effect on CO2. The real understanding, however, is that the relationship between KH, pH, peat, or any other source of hydrogen ions, and CO2 is linear
. What this means is that we can separate their contributions by appropriate experiments. I have done these experiments, and can post the experimental procedures, if anyone is interested in that. For now, I will give you the upshot:
You can measure pH, KH and compute "apparent" CO2 in the water, with the CO2 OFF in your tank. You will get a number. Let's say that number is 15 ppm. You also know that the water contains 3 ppm CO2 equilibrium level. This means that the peat is adding 12 ppm "CO2 equivalent" of acid to the water. Now you start CO2 injection and read pH, KH again. You look at the chart and it says 30 ppm. Subtract the 12 ppm from the 30 ppm, get 18 ppm. That is how much CO2 you have now.
One of the difficult parts here is the starting and stopping of CO2, and gathering of readings. You will need to take a lot of readings to get an understanding of the settling time of your aquarium, and its cyclic variations during the day/night. I spent several days with the CO2 OFF, then days more with it ON. However, this is effort well spent, becasue it allows you to add peat to your water, or like me, to add CO2 to an old aquarium that has reached a point where it is like a black water swamp without any peat.