for CO2 @ 30ppm
- kH 1: pH = 6.0
- kH 4: pH = 6.6
Have I got that wrong?
or do I need some fresh air
Not sure what youre doing. You are supposed to do from pH at equilibrium (which is whatever pH has a CO2 ppm of around 1.5) down to the pH at which you get 30 ppm CO2. This for each kh that you want.
I think what you are doing is comparing the pH for 30 ppm CO2 for each kH. This is not what I mean.
What I mean is the "jump" of pH for the same water (not at different khs)