I agree with you. My confusion, as I am not in aviation, was with the (for obvious reasons) aircraft usage of weight of fuel versus volume. I was calculating weight/volume for the ppm addition as the amount was reported in kg.
Using your numbers of 7000 L fuel to achieve 100 ppm by volume....
I understand. Anyway, this stuff is so simple and it's so easy to generate a simple spreadsheet or graph to do it automatically........ Kg fuel in, addition rate calculated.