How to calcuate simple saturation indices

[Rachael]

Hello-

First time Phreeqc user here, and I only know a couple of commands. I need to answer the following question:

"Calculate how much gypsum can be dissolved in dissolved water using a Ksp value of 10^-4.602"

How can I set the Ksp value in Phreeqc?

Thanks

[dlparkhurst]

You need to use PHASES, SOLUTION, and EQUILIBRIUM_PHASES data blocks.