I prepared an isotonic solution of table salt in water following this recipe: 1 leveled coffee spoon of salt in 0,5L of water.
9g/L would be an isotonic solution, a leveled coffee spoon is commonly given as 5g - close enough. I use water from the tap, which was freshly boiled in a water cooker. The water is not chlorinated, I don't know the hardness.
However, even given hours of time, a significant amount of salt doesn't go into solution - visible as turbidity/precipitation. How can this be?
I need the solution to flush my child's nose, so I don't want to use too much salt.