I have posted this before, but Mason, one of the early proponents of the sequential dump and fill showed mathematically and in practice that this method was not as effective as a stream of continuously running water for washing film or paper. He therefore repudiated the dump and fill method. I posted the equations in another thread on this same subject which keeps coming up over and over.

The best wash is a stream of constantly flowing water which is kept up until the photomaterial tests free of hypo residue and silver halide using the appropriate tests. The only way to change this is to change dC/dT or the change in concentration in the photoproduct with respect to time and this can only be changed by changing dD/dT or the change in diffusion rate of the unwanted materials with respect to time.

I've been working on this problem for over 3 years.