Place your cleaned elderberries into a stock pot and add enough water to almost cover the berries.
Bring to a boil and then lower heat to simmer for 20 - 30 minutes.
Strain berries through a juice strainer or jelly bag for 30 - 60 minutes.
Measure your juice. You will need 4 cups for this recipe (you can double the recipe if desired). Add water if needed to get 4 full cups.
Combine the elderberry juice and lemon or lime juice in your cleaned stock pot.
The package of Pomona's Pectin contains 2 smaller packages. One is pectin powder and the other is calcium powder. Put 1/2 teaspoon calcium powder and 1/2 cup water in a small jar with lid. Shake well. (Any leftover calcium water will last for several months in the refrigerator, or may be frozen indefinitely).
Stir 4 teaspoons of the calcium water into the elderberry juice and stir well.
In a separate bowl, combine sugar and 4 teaspoons of the pectin powder. Mix thoroughly.
Bring the elderberry mixture to a full boil. Add the sugar-pectin mixture. Stir constantly for 2 minutes to dissolve the sugar and pectin. Return to a full boil.
Remove from the heat.
Ladle the jell into clean, hot, 8 ounce canning jars to 1/4" of top. Wipe rims of jar clean and screw on 2-piece canning lids. Process in a hot water bath for 10 minutes.