modify PhreeqC database

[jedreiergeo]

How specifically can I modify the PhreeqC v 3.6.2 database. I am new to this so I need fairly detailed instructions

[dlparkhurst]

I need fairly detailed information on what you want to do.

First, there are multiple databases that are distributed with PHREEQC. Most are ion-association models, but Pitzer and SIT databases are also distributed.

For ion-association models, the basics are SOLUTION_MASTER_SPECIES, SOLUTION_SPECIES, and PHASES data blocks. Pitzer and SIT databases require PITZER and SIT data blocks. Check out the descriptions of these data blocks in the manual. Any definitions you put in an input file will augment or replace definitions in the database that you use.