For me it was fractions. I hate fractions.As long as it doesn't go beyond partial differential equations or transformations of any sort, I should be able to follow.
That's a fantastic chart; I ended up just taking photos at various times as a reference!Here is a color chart - i find this very helpful
if you don' t have a reference solution just ignore the bottom row. The colors in the top row tell you where you are in terms of ppm CO2. Chart ONLY applies to quality dKH 4 solutions, if you use tank water for tap water to make your own solution then the comparison does not apply.