New plaster pool trying to dial in pH

[jkleintech]

Hey all! First off thanks to all of you who answer questions in here and write all this content Awesome site! Okay here we go...

3 months since plaster was sprayed. I'm taking over maintenance from the PB and the pH was off the charts on my Taylor K-2006 - over 8.0. I complained, they sent someone out 2/1 to get it all handled one last time. That maintenance guy told me the pH is always high on salt pools and that keeping my TA higher should help buffer pH rise but he doesn't typically chase pH on new plaster and blah blah. This all sounds wrong based on what I've been reading here.

My TA has consistently been around 125 but I think I need to shoot for ~70 to help buffer pH rise, yes?

I bought some muriatic acid, dropped the pH to 7.0 per Pool Math. Aerated for a day after the rain finally stopped and it seems like the pH is climbing ~0.2 per day but no change to TA. What am I missing here?

Edit: My pool math data should be open for y'all to see but I'm not sure how to post that in here or verify that's working.

 

[PoolStored]

3 months since plaster was sprayed. I'm taking over maintenance from the PB and the pH was off the charts on my Taylor K-2006 - over 8.0. I complained, they sent someone out 2/1 to get it all handled one last time. That maintenance guy told me the pH is always high on salt pools and that keeping my TA higher should help buffer pH rise but he doesn't typically chase pH on new plaster and blah blah. This all sounds wrong based on what I've been reading here.

pH rise will be higher with new plaster for 6-18 months.
Salt pools do not cause pH to rise faster.
High TA and low pH cause pH to rise faster.

My TA has consistently been around 125 but I think I need to shoot for ~70 to help buffer pH rise, yes?

Yep!

I bought some muriatic acid, dropped the pH to 7.0 per Pool Math. Aerated for a day after the rain finally stopped and it seems like the pH is climbing ~0.2 per day but no change to TA. What am I missing here?

Acid will lower pH and TA.
Aeration will raise pH.
Lowering TA doesn't happen in a day.
Use acid to lower pH, aerate or wait for pH to rise to 8. Repeat and TA will come down.
When your TA gets to 60-80 stop lowering pH so low (7.0). Should be somewhat stable at 7.6 to 8.0.

 

[pjt]

I think I need to shoot for ~70 to help buffer pH rise, yes?

The lower the TA, the slower the pH rise. At a lower TA, equilibrium will occur at a lower pH. TA of 50 or above is fine. You don't need a dedicated effort to lower TA, it will come down slowly as you add MA for pH control.

Managing pH and Total Alkalinity - Further Reading

www.troublefreepool.com

PH TA Relationship - Further Reading

www.troublefreepool.com

My pool math data should be open for y'all to see but I'm not sure how to post that in here or verify that's working.

We can see it.

 

[jkleintech]

Awesome thanks guys! I read those articles and they helped a lot.

I've been trying too conserve my reagents and using the 10mL sample. Given the drop in TA is (unexpectedly) less drastic than the pH drop, that's probably my issue - I'm using the lower-fidelity test and not seeing the drop at all. I dropped my pH from over 8.0 to 7.0, so I should've only seen about a 16ppm TA drop according to the table.

If that's the case and I need to drop my TA from 125 back down to 70, does that mean I'm going to have to do this cycle another 3.5 times to get it where I need it?

 

[PoolStored]

If that's the case and I need to drop my TA from 125 back down to 70, does that mean I'm going to have to do this cycle another 3.5 times to get it where I need it?

The Taylor test accuracy is +/- 10% on a 25mL sample. The accuracy on a 10ml sample would be +/- 25%

Just keep managing pH and TA will come down.

 

[jkleintech]

Okay great thanks!

 

[Newdude]

does that mean I'm going to have to do this cycle another 3.5 times to get it where I need it?

It takes what it takes. You can force the issue quicker by running a low 7 and aerating to keep spiking the PH, but IMO if it saves you a couple weeks of doing it the slow/natural way, you still have to manage the Ph during the time it saved you. So i don't see the benefit of getting there sooner for most people.

*disclaimer : i am impatient about ALOT of things, but not this.

 

[jkleintech]

i am impatient about ALOT of things, but not this.

Hahaha fair enough, thanks! I won't overthink it. I'm trying to heat the pool right now for the weekend anyway so aeration has just been slowing that process down quite a bit.