Paul --
Just an observation, perhaps something to consider. If the ph is truely a concern, have you accounted for the fact that in most cases, (at least as far as I remember) one is going directly from the stop bath into the fixer. It would aoppear at least in my mind, that one would be dragging a fair amount of stopbath into the fixer, would that not lower the ph significantly?
Not if the Fixer is alkaline or neutral and is ph buffered.

