That's going to depend on your dishwasher. Our dishwasher does a prewash even in eco mode. But the water won't get as hot (to save power) and it takes longer. O

That's going to depend on your dishwasher. Our dishwasher does a prewash even in eco mode. But the water won't get as hot (to save power) and it takes longer. On the other hand, the 30 minute mode only does the one main wash. Check your manual.