Ask the plants? Do they care ? I just dose in one go, cos the plants told me so !!!!!
The easiest way is to use the calculator at "James' Planted Tank" <James' Planted Tank - Dosing Calculator>.From the back of my (ageing) mind to go from grams KNO3 to ppm we have to go through Avogrado's constant, don't we. Anyone care to fo de math on a napkin for me.