Here's how to make your automatic dishwasher soap last 50% longer:
Mix 1 cup borax and 1/2 cup baking soda with 3 cups of your powdered dishwasher detergent. Store in a tightly closed container, and use the same quantity as you usually would. The baking soda also works to prevent spots on your dishes.
**NOTE** A word of CAUTION: If you have a home water softening unit in your home, the DO NOT use this formula, as it will react with the chemicals in your water. (It could permanently etch fine glassware!. )