Let those interested try this then:

And PKSP or pKsp = the negative log of the Ksp.

And you are correct with the size causing the stress to the extent of the ratio of the sizes times the pKsp values involved factoring in the excess halide outside of the crystal and etc......... It goes on and on and on, but a mixed Cl/Br is tough to calculate and was the weakest point in our model as the sizes were close but no match and the pKsps were close but no match. So, this is a difficult subject and I hate to go into detail. I could not afford the experiments that would be needed to work one out by trial and error.