> My apologies for bugging you about this, but I am having problems editing the PHREEQC database and the User's Manual doesn't offer any information. I think there is a lot of information in the User's Manual ;). > Two problems that I've encountered: > 1) I changed the equilibrium constant for Hfo_wH2AsO3 in Wateq4f and saved the edited version to a different file name, as a "formatted text (space delimited)" file. No other format seems to run. What is the format of the original file? I noticed that the edited version is about 50% bigger. The original file and all input files for PHREEQC are white-space delimited (tabs and/or spaces) ascii text files. You appear to be running Word or some other text processor, and I'm not sure what it is doing to the file, but it appears not to be good. You might try WordPad instead. PhreeqcI is an interface that lets you enter and modify phreeqc input (or database) files, which you may want to try (https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc). > 2) When I changed the equilibrium constant back to what it was in the original version (for Hfo_wH2AsO3, the value is 5.41) and run the same input file, I get a different result than when I used the original (unedited) database?. Any ideas as to why this is happening?!? No, I don't know what has happened, but all that is necessary is to include a SURFACE_SPECIES data block in your input file that redefines the one species Hfo_wH2AsO3. SURFACE_SPECIES Hfo_wOH + H3AsO3 = Hfo_wH2AsO3 + H2O log_k new_log_K_Here You can also change the database file as you have tried, you just have to make sure you use the new database file. In batch mode, the database file is the third argument in invoking PHREEQC. With PhreeqcI, this is done through Properties in the File menu. If you really want to know what you did, you can send the input, database, and output files that you used and I'll take a look. David David Parkhurst (dlpark@xxxxxxxx) U.S. Geological Survey Box 25046, MS 413 Denver Federal Center Denver, CO 80225
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