Try this.. 1 grapefruit
2 Limons
1 sweet orange
1.5kg/or/3 1/2 lbs Sugar
wash the fruit, peel it, scrape off the pith and shred the peel as finely or coarsely as you prefer.chop the flesh roughly. Tie the pips, pith and any coarse tissue in a muslin bag.
Put the peel, flesh and the full muslin bag into a large bowl. Add 2 litres of water and soak for twenty four hours.
Next day transfer the contents of the bowl in to a preserving pan. Bring to the boil, lower the heat and and simmer for one and a half hours.Remove from the heat and squeeze the muslin bag to extract as much juice as possible.
Return the pan to the heat and add the sugar, stirring over a low heat until the sugar is dissolved. Bring to the boil and boil rapidly until the setting point is reached. Remove from the heat and skim off any scum.
leave to cool slightly before stirring and bottling.
Good luck!