I'm about to try soak washing for the first time, with distilled water in trays, and I'm curious as to the minimum volume of water needed for an adequate bath. I was initially thinking two gallons per tray should serve but would like to hear from others with experience in this method.

I will use two deep trays for fb prints and and I've no residue fixer tester nor silver iodine to make my own, on hand. Does anyone have an alternative formula for a residue fixer test?

I plan to use the one hour-fifteen minute split time I've read elsewhere as a guide. What sort of capacity should I expect per gallon of water?