Zeolite: It can only replace the functions of most STPP softened water, but no other washing functions. And it has poor solubility, and keeps a suspended state in water. Easy to be adsorbed on the surface of clothes.
Sodium tripolyphosphate (STPP): A kind of organic chelating agent with the function of chelating the metal ion in a detergent solution. It can also soften the water and prevent the powder from agglomeration.