Since I want to target pH 8.2-8.3, 8.5dKH and 420-440 mg/l Calcium, and currently my values are pH 8.4, 7.5dKH, 420mg/l Calcium, I need to tred carefully not to have too high pH values. Since I had been adding dKH buffer the past week to raise the KH and stopped adding kalkwasser to lower Calcium (which is working by the way), I have been getting closer to these values. I am however now at a point where I cannot move forward as I used to, since it will push the pH above 8.4. The reason is this:

It is clear that with a pH of 8.4 and Alkalinity of 7.5 (2.6meq/l) I seem to have a lower CO2 value in my tank that I should have. So to fix this (without adding a CO2 reactor) I am going to stop adding dKH buffer and instead use Baking Soda for the next two-four days (and closely monitoring pH, Alkalinity and Calcium). Theoretically baking soda will not increase pH dramatically but will increase alkalinity. Once I have reached my target values, I’ll start adding kalkwasser with white vinegar (4ml / litre of kalkwasser). This should raise alkalinity without impacting too much on pH.