I don't know how it works with the Fuji film but the Kodak GBX comes as a pair and should last about a month. 1qt concentrate : 3 qts water but the bottles are graduated so you can mix a smaller amount in that ratio. Excellent results with x-ray duplicating film. Use a water "stop". Developing time is a matter of taste mine is 2 to 3 minutes depending on desired contrast. Also a red safelight. I have used that combo for many years.