I don't have the ROM or the documentation. I did not find a mention of the ROM in a quick scan of the issues of PPX Exchange.
A search of the PPX-59 Software catalog identified two programs related to swimming pool water analysis:
PPX 998039G TABEX Swimming Pool Test
This program will tell the user how much of certain TABEX chemicals to use after making test of the water. This program is ideal for swimming pool dealers who sell TABEX chemicals. 846 steps.
PPX 998022H Analysis for TABX Swimming Pool Chemicals
Calculates the amount of TABEX chemicals needed to correct the free chlorine, total chlorine, ph, total alkalinity, cyanuric acid, iron and copper. Faster execution time than the first revision. 868 steps.
Both programs use the PC100.
The author of both programs is William B. Mentzel, Jr. of Huntington, Maryland. You might try to find him, but that is long time ago.
The second program was listed in the June 1982 H Update to the PPX-59 Software Catalog.
Neither program is in the PPX Library at Viktor Toth's site.
In 1989 TI PPC Notes published a list of several hundred PPX programs which were available for loan. Neither program is in that list.
I do not know if TI can help.
Palmer