chemistry mystery

[Greta]

Since Thursday and the incremental addition of muriatic acid, the pH has come down from 8 to 7.2, but, alas, the TA has only come down from 150 to 125. Now that pH is so low, how do I bring down the TA? And, the CH is at 450! How do I bring that down?? Tech support from Taylor Kits said there may be copper or iron in the water, preventing the calcium test to render a true blue, and suggested I add additional titrant R-0012 before the test, which I did and the end was still purple. Lots of metal, perhaps? Calcium, Alkalinity, and Metal, O MY!

 

[linen]

the pH has come down from 8 to 7.2, but, alas, the TA has only come down from 150 to 125

Lowering your ph for 8.0 to 7.2 will only lower TA ~13 ppm.

Now that pH is so low, how do I bring down the TA?

In pool school:http://www.troublefreepool.com/pool-school/lowering total alkalinity

And, the CH is at 450! How do I bring that down??

The only way to bring this down is to do a partial drain and refill. However, if you watch ph and TA, you can manage CH at 450 ppm. See: http://www.troublefreepool.com/pool-school/calcium_scaling

Tech support from Taylor Kits said there may be copper or iron in the water, preventing the calcium test to render a true blue, and suggested I add additional titrant R-0012 before the test, which I did and the end was still purple.

Add 5 drops of the R-0012 at the beginning. See the extended test kit directions: http://www.troublefreepool.com/extended-test-kit-directions-t25081.html#p206396

 

[Greta]

The pool is again draining...evidently I needed to tend to the CH before correcting pH and TA. The pool calculator recommended a 56% drain and refill with 0 CH refill. Hope municipal water isn't high.
On reducing the TA, the part I missed was the repetition of the process. Guess that could take quite a while. Maybe I'll get this figured out in time for summer of 2014.
On the testing for calcium, I did add the extra drops, and the end was still purple and not blue. Maybe the refill will correct everything. Thank you for your help.

 

[linen]

I was neglect in asking what kind of pool surface you have? What is it?

evidently I needed to tend to the CH before correcting pH and TA.

You can drain, but you can also manage the high CH without draining by keeping TA and pH a little on the low side. Either way works. Do you know how your CH got higher in the first place? Have you checked your fill water? Were you using Cal-hypo to chlorinate?

I did add the extra drops, and the end was still purple and not blue.

Not a big deal, then your CH is when it turned purple.

 

[Greta]

Pool surface is vinyl. No, I don't know how CH got so high. Originally, I was using the chlorine tabs, but the CYA was so high that pool store sold me Calcium caplets, same product as "turbo shock", which supplier reassured me had no CYA in it. But that's only been for the past 2 months or so, until I scrapped it all and started with liquid bleach. I have not checked fill water, but will. About 2-3 months ago, TA was low, so pool store sold me Alkalinity Plus. Then I had to drain due to high CYA. But lately, TA is too high, along with pH, so I've been adding acid. Now that's draining. In remedying one thing, I screw up another. I had a pool once before and had none of these issues. If city water is high, I'll have to manage it as you recommend, by keeping TA and pH low. How long does it take, ballpark, to raise pH using aeration? I have "fountain" attached to pool return.

 

[linen]

If your surface is vinyl, then for the most part you can ignore your CH (and csi). I was assuming you had a plaster pool. So stop draining!

You need to spend some time in pool school and take control of your pool and stop being jerked around by the pool store. The link is at the upper right, but don't be afraid to ask questions.

 

[JohnN]

I thought vinyl could scale just like plaster? I know low CH in vinyl doesn't matter.

 

[linen]

It can, but I have only heard of it with really high CH (600+) and poorly maintained other parameters.

 

[Richard320]

I thought vinyl could scale just like plaster? I know low CH in vinyl doesn't matter.

It can, but 450 isn't that high.

 

[JohnN]

Ahh, thanks. Luckily I don't have to worry at all, either way. My CH is 30 right now. I know you CA and AZ people wish you had that number. If it makes you feel better, I have to deal with iron.