About the OS of Phreeqc when kinetic reactions take place

[Pak]

For an splitting time step Phreeqc calculates the kinetics and equilibrium calculations  after advection and after a diffusion step. So

for a splitting dt:
1) Advection + reactions
2) Diffusion + reactions

I wonder if the time step of kinetics is the same in both cases, and if it is the whole splitting dt.

[dlparkhurst]

The total time step is divided into n equal increments, where n equals the number of dispersion steps plus one (for advection). The dispersion steps are arranged before and after the advection step.

At each of the n steps, kinetics is simulated with a series of sub time steps based on an automatic time stepping algorithms in the Runge Kutte and CVODE integrators (possibly with guidance from some of the KINETICS options). If the integration for one of the n steps exceeds an error tolerance, then the time substep is reduced further.