Wow...this is a job for the experts

[chem geek]

I am surprised since the alk is so low, I thought the ph would swing up more quickly.

If the pH were 4.0, then it would take about 5 boxes of Borax to raise the pH to 7.0 and almost 7 boxes to get to 7.5

If the pH were 3.0, then it would take about 11 boxes of Borax to raise the pH to 7.0 and 13 boxes to raise the pH to 7.5

So it would seem that you need to keep going. If you use Borax, then you will end up with high levels of borates in the pool. Each box of Borax adds about 3.6 ppm Boron (Borates) to the pool. So a positive side effect of raising the pH in this pool is that it will be close to having the algicidal properties of the pool that is talked about in this thread.

Richard

[CarlD]

Please beware that a pH maintained at 3 in a vinyl pool may well have already ruined the liner.

Sorry to be the bearer of depressing news....

[bluecamel]

Thanks for the great link on the borate experiment. We are moving the ph, but not as much as I had hoped. (30 drops of base demand now puts me at 7.2).

Once I get the ph in measurable range, is the next step TA? And should I keep it around 80 like the borate experiment? Also, I will retest the CYA, but I am sure it will be over 100. If so, I need to use the CYA/alkilinity equation, right?

Advice appreciated because I do not want to over do one thing trying to correct the other.

They know that their liner is probably toast. I actually think it was pretty dead when they moved in. The previous owners have been running a very clear/high chlorine acid bath for some time. They never used the pool so they only cared if it was clear.

[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

[CarlD]

Yeah here's hoping it's really thick vinyl so there's enough of a layer that isn't damaged, otherwise it's all for naught. Acid softens vinyl--some of the people who used the "slug method" to try lowering T/A found this out--you can SEE the vinyl wrinkling where the acid is destroying it.

Swimming in that? You might end up skinny-dipping when it dissolves your suits...depending on your POV this could be a bad thing , or a good thing !

I hate to be pessimistic, but I think this liner, if it's not toast, will have a much shorter life.

But, as Richard said, you are doing everything right.

[bluecamel]

Thanks guys. I will try the dilution cya test. My neighbors' heads are swimming from all the stuff I am throwing at them. But they are sending in their funds to become members and are on their way to being converts. I think they will drain some in the summer, assuming their liner makes it. They have been pounding the pool store chlorine the last 2 months since they moved in.

I know you have heard it before but, as always, you are great.