Racked it to secondary over a week ago, and bottled it a couple days ago. Definitely bitter, and fairly thick. Clogged up my tube while siphoning, making it difficult to bottle. So I figured I'd give it a second go, with a recipe in mind and taking notes in case it turns out decent.
For a 2-gallon batch
120 oz grapefruit juice (fresh from white grapefruits, juice and strained)
1 gallon of bottled water
1 liter White Labs English Cider starter
~4 lbs refined cane sugar
1 juiced lemon
Cooked the grapefruit juice+water+sugar+lemon for half an hour without bringing it to a boil. Cooled using submersion in ice water and pitched the yeast starter at room temperature. Tasted the fruit concoction and it tasted decent, but definitely sweet.
Came out to around 2.3 Gallons with an initial gravity of 1.085
Using 1 gallon glass jugs for primary, and fermentation took off within 12 hours.