Citrus Smoothie Recipe

6 1/2 cups ruby red or pink grapefruit juice, divided
2 cups pineapple juice
1 (6 ounce) can frozen orange juice concentrate, thawed and undiluted
2 cups lime-flavored sparkling mineral water, chilled
Garnish: lime slices or a strawberry

Pour 2 1/2 cups grapefruit juice into ice trays, filling 28 sections, freeze. Combine remaining 4 cups grapefruit juice, pineapple juice, and orange juice concentrate, stir well. Cover and chill at least 3 hours. Stir in mineral water just before serving. Place 3 frozen grapefruit juice cubes in each of 9 glasses, fill each fruit juice mixture. Garnish, if desired. Serve immediately.