potassium chloride
Do you mean this stuff? https://www.amazon.com/Potassium-Chloride-KCl-1-Pound/dp/B008NX2WJ8/ref=sr_1_5?ie=UTF8&qid=1491578398&sr=8-5&keywords=potassium+chloride+powder
And this stuff: https://www.amazon.com/Pound-Potassium-Sulfate-Potash-Organic/dp/B004JD6MGK/ref=sr_1_2?s=lawn-garden&ie=UTF8&qid=1491578452&sr=1-2&keywords=potassium+sulfate