Grapefruit Marmalade with Smoked Salt

In a medium bowl, whisk the sugar with the smoked salt and pectin.

In a large saucepan, whisk the grapefruit zest with the grapefruit and lemon juices and the calcium water and bring to a boil. Gradually whisk in the sugar mixture and bring back to a boil over high heat, whisking, until the sugar dissolves, about 3 minutes. Remove from the heat and skim off any foam. Test the marmalade: Spoon 1 tablespoon onto a chilled plate and refrigerate until it cools to room temperature, about 3 minutes; the marmalade is ready when it is thickened slightly and a spoon dragged through it leaves a clear trail. If the marmalade is too loose, continue simmering and test every 5 minutes.

Pour the marmalade into glass jars and let cool completely.