What type of detergent should I use in my GSD4500?

Use only detergent specifically made for use in dishwashers. Cascade®, Cascade® Complete, and Electrasol® Automatic Dishwashing Detergents have been approved for use in all GE dishwashers. Keep your detergent fresh and dry, and do not put powder detergent into the dispenser until you're ready to wash dishes.