In the previous point we have seen that the presence of a common ion decreases the solubility of salts. But, what happens if the ions present are different from those involved in the dissociation of the salt? In this case there is a slight increase in the solubility of the salt, called the saline effect. Thus, for example, the solubility of potassium nitrate in a sodium chloride solution is slightly higher than in pure water.
The increase in ionic concentration in the solution produces greater attractions between ions (increased ionic strength), which produces a decrease in activities (real ion concentrations) with respect to molar concentrations.
This decrease in activities forces a greater dissolution of the salt to reach the solubility product.