Help! High PH and Low Total Alkalinity

Jt1068

Member
Jul 13, 2022
5
Fort Mill, SC
My pool has been really good this year. Its a 30k gallon, pebbletec with a SWG. Ive got the TF Pro test kit and all the numbers have been pretty much in line all year. I typically run a little low on Chlorine and CYA - the pool has no shade and is west facing and gets blasted with Sun all day, but I typically can manage it.

However, I went away for Labor day for 3 days, and came back to Algae and a sad looking pool. I measured, and found High PH (over 8.2), TA of 70, 0 Chlorine and 0 CYA.

I ve been trying to bring down the PH but it seems stuck at 8.2 after 24 oz of Muriatic acid, and now my TA is at 50. I was trying to get PH in line before adding liquid chlorine and some stablizer / shock for CYA but am confused why PH is not moving.

Any help / thoughts would be appreciated!
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
40,605
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Welcome to TFP! :wave: You're stuck because your TA is so low you can't really get as aggressive with acid as you would like. But you need to increase the TA again before tackling the pH. I'd increase the TA back up to about 70-80 which should allow you to get aggressive and consistent again with the acid, at least for a short time. Ideally you want the pH in the low 7s for the SLAM Process, but just do the best you can then start the SLAM. Later, don't be surprised with a SWG if your pool's pH likes to hoover around 7.8, so if you can keep it in that area that's a good thing.

Continue to work the CYA from zero to 30 in preparation for the SLAM. Use liquid chlorine to increase and maintain the SLAM FC level of 12 and press-on with the SLAM Process until you pass all 3 criteria. Hope that works for you.

Let us know if you have any problems.

Also see our Pool Care Basics page for lots of great info.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
38,900
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Welcome to TFP.

Add 30 ppm of stabilizer/CYA and get it dissolving in your pool. It is a mild acid and will help lower your pH.

Add about 8 ppm of liquid chlorine and maintain that. Don't let your pH problem distract you from maintaining your FC.

What % MA are you using? 24 oz of 31% will lower your pH by 0.2. Give your pH a day to recover and add another 24 oz. Depending on how high your pH is it may take a few additions of MA to get it into the 7's.

Once your pH is around 7.4 you need to follow the SLAM Process with a SLAM FC of 12.
 

Jt1068

Member
Jul 13, 2022
5
Fort Mill, SC
Thank you both. Added some stabilizer and CYA is now about 30. Added liquid chlorine. and now chlorine is about 2 on the scale and PH is back to about 7.6. Algae has nearly disappeared and water is looking much clearer.

Am keeping a close eye on it.

(I am using MA at 31%).
 
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reggiehammond

Gold Supporter
Oct 4, 2020
705
Fort Worth, Texas
Pool Size
30000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60 Plus
Thank you both. Added some stabilizer and CYA is now about 30. Added liquid chlorine. and now chlorine is about 2 on the scale and PH is back to about 7.6. Algae has nearly disappeared and water is looking much clearer.

Am keeping a close eye on it.

(I am using MA at 31%).
Sounds like you might be using the OTO chlorine test - the tube next to pH. That’s generally pretty worthless; use the FAS-DPD test included in your kit. It’s accurate above 5ppm, while the OTO is not.
 
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