Hm, I don't think I add more then necessary. Even in the pinned thread about which soils to use they talk about this stuff (dolomit, potash and crushed shells). I'll just add a bit of KCO3, crushed egg shells and Dolomit powder to my potting organic soil mixed with garden top soil and cap it with my gravel. Nothing really complicated and how I did all the other tanks. I just made a list of things I bought to get a feeling how expensive this project is. Maybe thats where the confusion stemms from?
I also didn't really need to tweak anything so far, the tanks run very smoothly (except the one with the cloudiness and that does only affect the looks).