Can't get pH to come down


New member
Feb 13, 2019
Hi Everyone,

I just moved into a house in February with a pool. This is the first time being a pool owner, and I've been learning a lot on the site. Thank you!

My test results earlier today were:
FC: 0.0
CC: 0.0
pH: 8.2
CYA: 60

This is pretty typical of what I've been measuring, and I've been measuring the FC/CC and pH more-or-less weekly.

I added a gallon of 8.25% bleach and 2 quarts (64 oz) muriatic acid (20%).

I came back in about an hour and a half and have these results:
FC: 3.0
CC: 0.0
pH: 8.2

I don't seem to be able to affect the pH in the pool. I've added over a gallon of muriactic acid (31.5%) already over the last few weeks. But I've never gotten a pH test result less than the top color of my kit.

I know the waterfall is supposed to cause pH to climb, but in my case, it never seems to move down to start climbing back up.

Am I doing something wrong in the testing or do I just need to keep adding muriatic acid until the pH moves?



Bronze Supporter
Sep 23, 2015
I’m not a math whiz, but if a gallon of bleach raises your FC to 3 then 2 quarts of acid should have lowered your ph.

Where are you getting your acid from? Did it have a seal at the top? Maybe someone bought some, used it, and filled it back up with water to return it to the store? There is no good explanation for this that I can think of......

Maybe add a drop of acid to your ph test and see if it makes a difference.

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Hello rum and welcome to TFP! :wave: Let's back-track a bit and get more info so we can get you on track.
1 - Your test kit. The best Leslie's has is the Taylor K-2005. If that's what you have, you will need to add the FAS-DPD to that for better accuracy. This will make your K-2005 a K-2006 test kit which is much better for FC testing.
2- Next time you post, please include all test results (FC, CC, CYA, pH, TA, CH). We need to see them all to evaluate your water. Include your water temp if you can.
3 - What part of TX are you at? You should add the city to your location since San Angelo is a lot different than Corpus.
4 - How are you chlorinating on a daily basis? Are you using that inline (tabs) all the time?
5 - How long do you run the waterfall and/or any other items that may create aeration?
6 - How old is the pool/plaster? If you know.

That info will help tremendously. I will say that lowering pH is directly related to the other numbers and your water temp. Lowering pH is generally straight-forward when using the full strength 31.5% muriatic acid, dosing according to what is needed by using the PoolMath tool. But we can come back to that once we get more info. Stick around, we'll help.
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Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

You left off your TA test number.. TA and pH go hand it hand, you really need both test results to know what to do...

In a 16000 gallon pool it should take 70 oz. of full strength MA to reduce your pH by 1.0..

That does not mean "over a few weeks" that means all at once. That also assumes your pH is 8.2 and not higher.

I suggest that you do two things. Shut off the water fall and leave it off for now. Add 70 oz. of 31% MA and wait an hour and see what your pH reads.. If not in the middle 7's add more MA per pool math.. Then measure your TA and report back..


Jim R.


Gold Supporter
TFP Guide
as mentioned you need to post a full set of test results, double check you are using the correct reagent
as the ph test maximum is around 8.2
hypothetically if your reading was 9.5 and you were using a weak acid it could take multiple adjustments
check what strength acid you are using then add enough to adjust from 8.2 to 7.4 with pump running
give the pool a brush and retest, repeat until you get a valid reading
if you add more than another gallon stop and repost your results


New member
Feb 13, 2019
Thank you for the prompt replies everyone!

As I was reading the replies, I realized something I had been missing. I knew that my pH test kit was only indicating that the pH was over 8.2, but not by how much. I had been putting 8.2 in the Pool Math app and adjusting as advised. What I realized was that I should be using the acid demand test in my kit to get a better indication of how much over 8.2 it really was. In doing so I maxed out the table Taylor provided. So I added that, about 2 quarts of 20% and another 10 oz of 31.5% (new bottle), and let is stew for an hour. Then when I measured the pH, it was a shade lower than the 8.2.

Then, I could use the Pool Math app effectively. It suggested another 12 oz to get to 7.5, and it worked!

I have also turned off my waterfall for now, but I've been running the pump to circulate the water.

I took a new chlorine reading, and it was at FC: 1.5 . So I also added 72 oz of 10% bleach. I let all that stew for an hour, and here are all my test readings.

FC: 5.0
CC: 0.0
pH: 7.5
TA: 210
CH: 440
CYA: 50
Temp: 70 degrees
CSI: 0.37

To answer some of the other questions:
3 - What part of TX are you at? I'm just south of Austin and using well water. That mean its coming out of a limestone aquafer and is pretty hard. Technically, I'm filling through a softener.

Being south of Austin also means that the pool is filling with oak pollen pods right now. :(

4 - How are you chlorinating on a daily basis? Are you using that inline (tabs) all the time? The inline tabs are the only thing happening daily, and from what I can tell they don't seem to be doing much. After 2 weeks they are about half dissolved, but there wasn't much chlorine in the water when I first started this thread yesterday.

5 - How long do you run the waterfall and/or any other items that may create aeration? The pump timer is set to run for about 7 hours a day, and the waterfall has been running continuously during that.

6 - How old is the pool/plaster? If you know. I don't know.

Thanks again for everyone's help and suggestions on taking care of the pool better.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
Welcome to the forum:wave:
That mean its coming out of a limestone aquafer and is pretty hard. Technically, I'm filling through a softener.
With a test result of 440 ppm CH, that suggests your water softener is not working or you are bypassing it with your spigot from which you fill.

Your refill water, using the softener, should be about 100 or less. Test the well water before it goes to the softener and post that up.


New member
Feb 13, 2019
OK, I couldn't identify a tap that I can access before the water softener. So I took readings at my kitchen sink to see if it was different.

Kitchen Sink:
FC: 0.0
pH: 7.2
TA: 400
CH: 50!

So it looks like that spigot outside is plumbed before the softener; although, I can't figure out how. I'll take some readings directly at the faucet next time.

Just for fun, I took readings from the RO faucet at my sink. It is just a small, under-the-sink system.

FC: 0.0
pH: <6.8
TA: <50
CH: 0

Does anyone know if RO systems typically turn the water a bit acidic?

I have no idea what these TA readings mean for the water quality.

Do people normally fill up a pool through a home water softening unit? I actually thought it was weird and wasteful that I was doing that, but I couldn't find a way around it.


TFP Guide
May 10, 2017
Hays, Kansas
Yes ro does and drinking that water and most bottle water is unhealthy.

To fill from a softener requires knowing your softner and is most of the time a good idea if you correctly set it up