this is my calculation:

((weight of fert in grams/weight of water)*10^6)*percetage of K in kno3 molecule= x ppm

i do that for k2so4 too , and combine results.

This are percentages of K atoms in molecules:

K% in kno3= 38,672%

K2% in k2so4=44,874%

Is that calculation and data ok?