How much detergent should I use based on my water hardness?

The amount of detergent depends on whether your water is hard or soft. With hard water (7-12 grains), you need extra detergent to get dishes clean. With soft water (0-3 grains), you need less detergent. For a Normal Wash cycle with soft water, use 1 tablespoon in the main cup and 1 tablespoon in the open cup minimum; with hard water, fill both cups completely full. Your water department can tell you how hard your water is.