CYA

[blsobx]

Last Saturday I had to add 64oz of Cya. My ph was 8.2 the cya lowered it to 7.2. Now my ph is back to 8.2, I still need to add some more cya. Do I add cya first and then work on ph?

 

[mikemass]

You're SWG may be causing the rapid pH bounce. If you have a high TA that will just make the bounce more rapid. Post that reading. While you are at it, might as well post all results because someone will inevitable ask for it. As for your question, I would continue to manage that pH down to the 7.4 ish as it will tend to rise it appears. You can dissolve some more CYA and manage the pH simultaneously.

 

[Texas Splash]

I would note that you mention using CYA to lower pH, but CYA doesn't lower pH. Not sure if you got your terms swapped as it's muriatic acid (not cyanuric acid) that lowers pH. Just wanted to be clear and not confuse anyone later who may read your post. Assuming you did indeed mean to say "muriatic" acid to power pH, you'll want to refer to the Pool School - Lower Total Alkalinity page for more details.

Now if you truly did add "cyanuiric" acid (CYA/stabilizer), then you may now have a whole different problem.

 

[mikemass]

Good point by TXSplash. CYA is acidic, but not enough to drop the pH that much.

 

[blsobx]

My TA is 176. My cya is 50.

- - - Updated - - -

No I added the cya and it lowered my ph. I have muriactic acid but I was trying to adjust cya first.

 

[Texas Splash]

Okay then, you'll want to use "muriatic" acid as noted on the Pool School - Recommended Pool Chemicals page to lower pH. Take the pH all the way down to 7.0. Use aeration to raise the pH all the way up to 7.8, then hit it again with muriatic acid and repeat the process.

In a day or two, I would suggest checking your CYA to ensure you didn't shoot that number too high.

Good luck!

 

[blsobx]

Added muriatic acid how long before I can test?

 

[Texas Splash]

I'd let it mix real good for at least 30 min after adding acid then re-test.