Gh Booster problem

Hi all, i recently purchased a Gh Booster with the following analysis:

K 13.5% (K2O 13.2%),Ca 9% (CaO 12.5%), Mg 3% (MgO 5%)

It states that 1tsp added to 100Lt adds 1dGH

My tank has 10gal, dosing 1/2 EI, so about 15ppm of NO3 and K weekly.

If my calculations were correct, i converted 1 tsp to 4.92g so that would give me 11.8g to add to my tank raising 6 dGH, but with that amount, i would be adding a wooping 150ppm of K?

Maybe i did something wrong on my calculations, can someone help me?