I was a bit confused as to your user name at first, but that's another story.
In any case, you cannot measure pH and kH to get CO2 reliably, as there are other factors in aquarium water that will affect the kH.
The best way to check CO2 levels is to use a drop checker with a 4 dkH reference solution.
Hhehehehe....Tom turned newbie and talking about CO2 chart.
For the OP, the CO2 drop checker should be somewhat yellowish by mid day. Completely yellow by the end of the light cycle. Well, you talked about grams of fert. Do you know how many ppm of each fert you are dosing? How do you dissolve your CO2 given that you have a 100g tank? Is a big tank.