I bought potassium sulfate to be used as a fertilizer. The fertilizer comes in the form of small pebbles 1-2mm in diameter. Wikipedia states that the solubility is around 111g/liter at 20°C.
I tested several concentrations
100g / liter
50g / liter
25g / liter
at room temperature (22° C). After 2 hours there are still solids remaining in the solution. The water here is hard (EC= 0.6ms / cm) which hinders the dissolution. What can I do to improve the solubility of this fertilizer in water apart from heating, using reverse osmosis, grinding the pebbles or vigorous shaking of the solution (which worked) but is very tedious.