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

For soft water (0–3 grains hardness), use a minimum of 1 tablespoon in the main cup for a Normal Wash cycle. For hard water (7–12 grains), fill both the main cup and open cup completely full. A filled main cup holds 3 tablespoons and a filled open cup holds 2 tablespoons. At 12 grains and above, a water softener is recommended.