Treat Plus-X like FP-4+ (a better choice, BTW) and you'll be very close. At least, a good starting point. Re-read the recommenations for solution volume. On page 58, Gordon says that one litre of working solution will develop 320 square inches of film, or 16 sheets of 4X5. I use 500 ml per 6 sheets of 4X5 in trays. One litre per 4 sheets 8X10.(posted 9179 days ago)