How do we count or read the ppm in NO3? I am reading the NO3 through the card that it cames when buying from the retail box. only show in mg/l.

And, any good way to increase the NO3?........one thing, recently I have read it from the forum, Carbon/charcoal will absorb all the nutrients. But when I run thrrough the Natural Aquarium World: Book 3, it stated that using Charcoal in the filter......any difference with or without?