Bring to a boil, boil 20 minutes.
Add grapefruit and lemon juice.
Drain through cheesecloth, do not squeeze.
Place strained liquid in pot, add 5 1/2 cups sugar and 1 bottle pectin.
Bring mixture to a boil and boil 5 minutes.
Skim off foam.
Pour into jelly jars.
Seal with paraffin or seal with lids and place in water bath.
