Before you start:
The rest time is critical. Be sure to pick fruit with plenty of seeds. They hold the wizardry of pectin that makes the mixture gel. If you don't have enough pectin released due to the amount of seeds or time, you may need to use some pectin to get your solution to gel. Be sure to buy real fruit pectin.

This stores very well in the fridge or can be easily canned.

Ingredients

1 1/2 pounds oranges
1 1/2 pounds grapefruit
1/2 pound limes
1/2 pound lemons
water to make up 7 cups liquid
6 cups sugar
pinch salt
pectin (if necessary)

Instructions

1. Cut citrus in half horizontally then cut each half into quarters.
2. Squeeze each piece over a mesh strainer. Remove but retain seeds. Membrane and pith should be discarded, but pulp should be added back to the liquid.
3. Using a vegetable peeler, start at the point of one of the peels, lay the peel flat and then peel the entire "skin" wiggling the peeler as necessary.
4. Julienne the peels and then chop them into pieces no longer than half an inch. Mix them all together in a bowl.
5. Place the seeds in a mesh tea ball or tie them up in a bit of cheesecloth.
6. Place 3 cups of juice, 2 1/2 cups of zest and the seeds in a large saucepan. Heat over medium high heat until mixture reaches a full boil. Reduce heat and simmer for 25 minutes.
7. Remove from the heat and pour into a measuring bowl. Add enough water to make the mixture 8 cups.
8. Place in the refrigerator for at least 8 hours or overnight.
9. Place mixture, sugar and salt in a large pot over medium-high heat. Bring to a full boil. Reduce heat to a low boil and continue to heat until mixture reaches a temperature of 220 degrees (gel stage) on a thermometer.
10. About halfway through the cooking process, remove the seeds.
11. Test your marmalade at this point by spooning a bit onto a plate and placing it in the freezer for 3 minutes. If it crinkles up and looks as though it is beginning to gel it is OK to remove the remainder from the heat. If not, you may consider adding the pectin gel at this point.
12. Pour the marmalade into warm, clean jars. If you are going to be using it right away or giving away as gifts to be used right away, it can be kept in the refrigerator.