besides help drying the dishes, it seems to have something to do with hard or soft water of different areas. My machine has a slot for you to put the aid in (just put in once and it can go for quite a while), and the setting lets you increase or decrease how much to release. The manual says that if there are too much aid in the water, the dishes will come out with some bubbles on; if too little, the dishes will still be wet with streaks of water.