PH rising rapidly 35 day old plaster, going to lower TA

n8huntsman

LifeTime Supporter
Apr 5, 2009
232
Plaster is about 35 days old now. I have put about 10 gallons of muriatic acid in already and it still comes right back up. Does this seem excessive? I'm going to try to lower the TA by aerating. Do you think my 3 24" waterfalls, spa spillway, and spa jets are enough to aerate, or should I make something that brings the returns up out of the water? Does it matter if I aerate all at once to get it done quickly, or can I just do it over several days through normal operation so I don't have to run the pump all night?

Thanks in advance!
 

JohnT

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Mod Squad
TFP Expert
Apr 4, 2007
9,620
SW Indiana
I imagine your new plaster and all of the aeration you get is responsible for the pH rise. TA is probably a minor effect, and just running the pool is going to lower it as you compensate for the plaster and aeration.

My bet is your pool will always be hard to control pH with all the aeration, but it should get better after the plaster gets a year or so on it.
 

JasonLion

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May 7, 2007
37,880
Silver Spring, MD
You should be almost done with the lots and lots of acid period. Fresh plaster typically raises the PH rapidly for about a month, and then more slowly for up to a year.

Your waterfalls are great for aeration.
 

n8huntsman

LifeTime Supporter
Apr 5, 2009
232
I just tested the TA and it was acutally only 80 so I guess I wont be trying to lower it. I havnt checked it lately and thought it was higher. PH was back up to 8 or higher so I dumped in another gallon of 14.5% muriatic acid. Is Home Depot's price of $5 per gallon a decent price for that stuff or should I look elsewhere?
 

JohnT

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Mod Squad
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Apr 4, 2007
9,620
SW Indiana
n8scstm said:
I just tested the TA and it was acutally only 80 so I guess I wont be trying to lower it. I havnt checked it lately and thought it was higher. PH was back up to 8 or higher so I dumped in another gallon of 14.5% muriatic acid. Is Home Depot's price of $5 per gallon a decent price for that stuff or should I look elsewhere?
Get the 31.45% and you won't go through so much, and you can get it for less than $10 a gallon.
 

n8huntsman

LifeTime Supporter
Apr 5, 2009
232
The lowes by my house doesnt have the 31.45. They have the same 14.5 as HD for the same price. Any other ideas of where I can find the 31.45? I'm still using a gallon of acid everytime I turn on my waterfalls.
 

chem geek

TFP Expert
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Mar 28, 2007
12,083
San Rafael, CA USA
If you know that turning off your waterfalls has the pH not rise as quickly, then you can lower your TA even further to reduce the pH rise effect from the waterfalls. I wouldn't go any lower than 50 ppm and you should try 60 ppm first, but if you lower the TA you'll need to raise the CH to compensate. In the short run, just see if the pH rise slows down when the pH is around 7.8 and the TA is lower. If it is, then you could adjust the CH later and target the pH down a bit.
 

n8huntsman

LifeTime Supporter
Apr 5, 2009
232
Ohm_Boy said:
I'm going to try to lower the TA by aerating.
Not to belabor the point, but aerating does not lower TA.
Adding acid lowers the TA as well as the PH. Aerating just facilitates raising the PH back up.
I know. I meant lower the TA by using the aerating procedure as a whole. Wasn't just going to turn on the waterfalls.
 

n8huntsman

LifeTime Supporter
Apr 5, 2009
232
chem geek said:
If you know that turning off your waterfalls has the pH not rise as quickly, then you can lower your TA even further to reduce the pH rise effect from the waterfalls. I wouldn't go any lower than 50 ppm and you should try 60 ppm first, but if you lower the TA you'll need to raise the CH to compensate. In the short run, just see if the pH rise slows down when the pH is around 7.8 and the TA is lower. If it is, then you could adjust the CH later and target the pH down a bit.
Raise the CH in Southern California? I've never heard of having to do that here.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
I was assuming that your saturation index wasn't already too high. You should use The Pool Calculator to see where you are at after you've adjusted the TA and the pH is stable where you want it. You are right that you may not need to adjust the CH if the saturation index is still OK.