Trying to make a KCl solution but the potassium chloride doesn't seem to dissolve. I use RO-water and tried 150 g/L (well below the max solubility) but the solution stays whitish. Not like milk but you can't see far through. Also there are still some crystals on the bottom. The KCl is brewsalt for water treatment. Might this be not pure enough? Or how do I check whether it is KCl at all?