Since Diafine has an almost infinite shelf life, and does not deplete with use in the traditional replenishment sense, I use
about a half gallon of liquid in a large 3 1/2" deep tray for developing 8x10.
Development uses straight stock solution, not diluted, which is returned to the storage bottle for re-use.
One caution... DO NOT pre-soak the film, regardless of any contrary instructions from the film manufacturer.
I normally develop six sheets at a time, emulsion down. It's a compensating developer, so minimal agitation.
I use four trays, one each for Solution A and Solution B, followed by regular indicator stop bath and rapid fix.
Wash, PermaWash, second wash, PhotoFlo, and dry as usual.
The critical thing about using Diafine is avoiding contamination. You should have a complete separate set of tray, graduates,
containers, and utensils for Solution A, and not use those for anything else. Even slight contamination will ruin it.
I really love Diafine for tray development because it's insensitive to time and temperature. As long as the temp is
70°F-85°F (not < 70) it's happy. Time is from 3 to 5 minutes in each solution, with no difference in results.
These features make it ideal for tray development IMO.