New plaster, high ph after adding acid yesterday

[CarolinaCamper]

I am new to plaster pools, but not new to pools. I used to have an above ground pool. Moved to a house with an inground pool that i had resurfaced. I understand that pH will remain high for several weeks (months?) and I will need to add lots of acid. Yesterdays test showed a pH of 8.0 or higher. I added 16 ounces of muriatic acid. Today the pH is still showing as 8.0 or higher. Pool math says that I need to add another 15 ounces of muriatic acid. I kind of think that my pH is even higher than 8.0 but I don’t know how to figure out what it is. I have the Taylor K 2005 test kit.

EDIT: approx 20k gallons



For what it’s worth, my alkalinity is only 40. I’m going to add some baking soda today.

Lisa

 

[Toxophilite]

I am new to plaster pools, but not new to pools. I used to have an above ground pool. Moved to a house with an inground pool that i had resurfaced. I understand that pH will remain high for several weeks (months?) and I will need to add lots of acid. Yesterdays test showed a pH of 8.0 or higher. I added 16 ounces of muriatic acid. Today the pH is still showing as 8.0 or higher. Pool math says that I need to add another 15 ounces of muriatic acid. I kind of think that my pH is even higher than 8.0 but I don’t know how to figure out what it is. I have the Taylor K 2005 test kit.





View attachment 392415For what it’s worth, my alkalinity is only 40. I’m going to add some baking soda today.

Lisa

I'm new plaster owner and new here as well. About 3 weeks of me maintaining from PB. Best advise, don't add anything and wait for a response from someone here. When my Ph creeps up that high, I need about 1 gallon, sometimes more, to bring it back to normal on 15.5k gallon pool. Don't see your pool size listed, so again, wait!!!

 

[YippeeSkippy]

Hello Lisa, welcome to TFP
Let me share some info for new plaster- Have you read these?

Plaster Start-Up Guides - Further Reading

www.troublefreepool.com

Plaster Installation and Maintenance - Further Reading

www.troublefreepool.com

How low are you striving to go with the pH with those Muriatic Acid additions?

As a sidenote- your test kit is slightly inadequate. You're missing the *very* important FAS-DPD test for FC and CC tests over 5-10ppm. You can obtain the missing element here: FAS/DPD Chlorine & CC's test

Maddie

 

[stinsontx]

Welcome to TFP! I recently replastered my 19-20K gallon(ish) pool with traditional white plaster this year. My startup alkalinity was 110 which I am now keeping at 80. I took over the maintenance of the chemicals and brushing on day 4 when I realized the pool service company was sort of "checking out".

So far the pool has required about 1.75 gallons of muriatic acid (31.45%) since startup (41 days ago) which does not include the acid that the service company used for startup, which I know was quite a lot. I just dropped total alkalinity 10ppm yesterday which required about 50 fl oz of acid and took the PH from 7.9 to 7.7.

 

[Dirk]

When you get that purple color like that, you don't know what the pH actually is. It could very likely be higher than 8.0. The only solution I know of is to treat it like 8.0 and add the amount of acid to bring it down to your desired pH. Wait 30 minutes or so (with pump running) and then test it again. Still purple? Repeat the process. Continue to repeat the process until you get the color that indicates your desired pH. If this same process is needed the next time you test pH, then you can do it again, but better yet is to increase the frequency of your pH testing. If you never let it get higher than 7.8, then you'll always know where you're at...

I don't know what the theoretical limit of pool pH is, but I didn't want to find out with my new plaster. I felt it was important to try and keep the pH very stable and as close to the correct level as possible, at all times (I still do). pH is always important for plaster longevity, but never more so than when it is new. So I tested as often as it took to keep that pH exactly where it was supposed to be. I'll let you know in 20 years if that MO pays off!

I now use an automated system to maintain my pH, so it is virtually dead-on all day, every day.

 

[mknauss]

With a TA of 40, pH will not rise very high. Mid 8's at most I suspect.

 

[CarolinaCamper]

I'm new plaster owner and new here as well. About 3 weeks of me maintaining from PB. Best advise, don't add anything and wait for a response from someone here. When my Ph creeps up that high, I need about 1 gallon, sometimes more, to bring it back to normal on 15.5k gallon pool. Don't see your pool size listed, so again, wait!!!

Thanks - I added my pool volume to my post. Appreciate the reply!

 

[CarolinaCamper]

When you get that purple color like that, you don't know what the pH actually is. It could very likely be higher than 8.0. The only solution I know of is to treat it like 8.0 and add the amount of acid to bring it down to your desired pH. Wait 30 minutes or so (with pump running) and then test it again. Still purple? Repeat the process. Continue to repeat the process until you get the color that indicates your desired pH. If this same process is needed the next time you test pH, then you can do it again, but better yet is to increase the frequency of your pH testing. If you never let it get higher than 7.8, then you'll always know where you're at...

Thanks! I thought you were supposed to let chemicals circulate a lot longer than that before retesting? I’ve always heard at least overnight if not 24 hours.

 

[CarolinaCamper]

With a TA of 40, pH will not rise very high. Mid 8's at most I suspect.

So I need to bring up the TA, right?

 

[mknauss]

Not necessarily. What is your CSI? That should be kept on the positive side of zero for new plaster.

 

[skimmerswimmer]

Not necessarily. What is your CSI? That should be kept on the positive side of zero for new plaster.

I think it depends on the surface. I had Pebble Fina installed and there was quite a bit of mottling and extra "cream" that needed to come off, so the pool company and Pebbletec recommended keeping the PH low with a slightly negative CIA to help with it's removal. I think I was keeping my PH around 7.0 for the first few months, while brushing aggressively.

 

[ajw22]

I think it depends on the surface. I had Pebble Fina installed and there was quite a bit of mottling and extra "cream" that needed to come off, so the pool company and Pebbletec recommended keeping the PH low with a slightly negative CIA to help with it's removal. I think I was keeping my PH around 7.0 for the first few months, while brushing aggressively.

Did that fix your problems?

 

[CarolinaCamper]

Not necessarily. What is your CSI? That should be kept on the positive side of zero for new plaster.

No idea since I don’t have an accurate pH reading. IF my pH is 8.0, the CSI is -.11, but it’s prob a lot higher than that.

 

[mknauss]

You are showing a CYA of 0. So all of your TA is carbonate. Your new plaster is adding TA. So be careful adding a bunch of baking soda.
Do not lower your pH below 7.6.

 

[CarolinaCamper]

You are showing a CYA of 0. So all of your TA is carbonate. Your new plaster is adding TA. So be careful adding a bunch of baking soda.
Do not lower your pH below 7.6.

Yes, that's correct. I haven't added CYA yet. I'm using granular cal-hypo for now and will add CYA once things level out. Will be switching to salt in a couple of months.

So is the TA of 40 not really a concern?

 

[Dirk]

Thanks! I thought you were supposed to let chemicals circulate a lot longer than that before retesting? I’ve always heard at least overnight if not 24 hours.

Some chemicals (like salt and CYA) can take that long, or longer, to test accurately. But you'll get a good pH test result soon after adding acid. Increase the time and/or pump speed if you want, but you don't have to wait overnight...

 

[skimmerswimmer]

Did that fix your problems?

It helped to remove most of the cream. but some of the mottling was due to troweling imperfections that have lightened but remain visible, especially in the shade.

 

[mknauss]

So is the TA of 40 not really a concern?

It is on the low side, but, with high pH, adding baking soda will simply increase the rate of rise of your pH. You can add 30 ppm TA worth of baking soda if you like. Just do not add more than that.

 

[CarolinaCamper]

It is on the low side, but, with high pH, adding baking soda will simply increase the rate of rise of your pH. You can add 30 ppm TA worth of baking soda if you like. Just do not add more than that.

Thank you! I'll be honest, with my AGP, I tested and adjusted pH and alkalinity at the beginning of the season and then didn't test it again unless there was another indication it was out of whack, and that pool didn't give me a lot of chemistry problems. So I don't really fully understand the interplay between alk, pH, CYA, chlorine, etc. I do superficially, but this new plaster is making me have to REALLY understand it.

I will just leave the alkalinity alone for now.

 

[CarolinaCamper]

Welcome to TFP! I recently replastered my 19-20K gallon(ish) pool with traditional white plaster this year. My startup alkalinity was 110 which I am now keeping at 80. I took over the maintenance of the chemicals and brushing on day 4 when I realized the pool service company was sort of "checking out".

So I'm curious - You said "traditional white plaster." Did you not have any aggregate added to your plaster? I would have been happy with plain plaster but the PB said that's not as durable. Yet this pool lasted 35+ years without being resurfaced. Not to say it couldn't have used it, but the pool itself was still usable till the last year or two when it got so rough that the kids couldn't swim in it without getting bloody toes!