To a large heavy pot add 7 cups of sugar, 6.5 cups of juice, and 2 tsp lemon juice. Bring to a rolling boil and add pectin. Continue with a rolling boil for a full minute. Remove from heat and skim foam. Immediately pour hot jelly into prepared jars leaving 1/4" headspace. Wipe rim and top with prepared lids, screwing the bands to finger tight. Place jars in prepared water bath canner, cover with lid and process for 10 minutes, adjusting for your altitude (see notes). For me it was 20 minutes. Turn off heat and allow canner to sit for 5 minutes before removing jars to a towel lined rack. Allow jars to cool undisturbed.