Wow...this is a job for the experts

[chem geek]

1) Get the pH at least into a normal range around 7.2 - 7.8 (or at least in the 7.0 to 8.0 that your test kit can measure). Do this first before anything else as the out-of-range pH is the most damaging factor to the vinyl and to pool equipment (copper heat exchangers, etc.).

2) Add sodium bicarbonate aka baking soda to increase the TA. Yes, you can shoot for a target of 80 due to the extra borates that act as a buffer and due to the very high CYA that also acts as a buffer. Also, with step 3 you don't have to shoot for high accuracy since you're going to be diluting everything anyway.

3) Try and measure the CYA by diluting with an equal part of tap water and remeasuring. Then multiply your measurement by 2. If you still measure more than 100, dilute with two parts tap water to one part pool water and try again and multiply by 3, etc. Based on your CYA measurement, you will have to do a drain and refill to lower the CYA. However, that's a pain to do and will dilute all of your other chemicals so you might just keep your fingers crossed and hope that the CYA will get lower over the winter (some users see this occur) and then deal with the high CYA in the spring, but with such extraordinarly high CYA I doubt it will get lowered enough. With the lower water temperatures, the risk for algae is much less.

And of course immediately stop using TriChlor tablets as the source of chlorine. Switch to using bleach and maintain chlorine levels using bleach (or chlorinating liquid). Unfortunately, with the very high CYA levels a high chlorine level will be needed, but at least with the winter low water temperatures, the risk for algae will be low. You mention the CYA/alkalinity equation, but I think you mean the chlorine/CYA relationship as found in Ben's Best Guess CYA Chart. Let us know the actual CYA number when you get that figured out and we can tell you the chlorine level to maintain (or perhaps to just do a partial drain/refill now if the CYA is astronomical).

It's a good thing these people never used the pool. It truly sounds like an acid bath, though most carbonated beverages have a pH between 2.4 and 3.2. Nevertheless, the worst effect of swimming in such an acid pool would be on the eyes (that would sting like crazy and could even be harmful) while certain swimsuit fabrics would likely degrade. I'm sure it's not good to expose skin to such an environment, but don't know how long it takes to cause problems.

Hang in there -- you're doing great. And as Carl said, this pool may be totally ruined as the acidity may have destroyed the vinyl as well as any metal parts, especially copper as would be found in a gas heater.

Richard