Lowering PH

[cacciato2006]

Hello everyone. New to the site. Just purchased a pool that came with a home. ha I've spent a full work week cleaning and trying to understand the pool mechanicals and chemistry. I dropped CYA from 115 to 50 with a partial drains. Water is clear but the Polaris is not doing a good job so I ordered a robot earlier.

FC 1.5
PH 8.1
TA 240
CH175

FC/CH both need to come up, and PH and TA down. Prior to today I was using a test strip that must of been topped out on PH since it always read 8.2. Over the last week my records show I had put in 215 Oz of 31.45% MA and today with the TF-100 kit I found that the PH was still 8.1. Previously with the test strip the TA measured 240 and I got the same thing today with the TF-100 so there has been no apparent change. My goal is to drop the PH to 7.0 and aerate to drop the alkalinity and pool math said 2 more gallons of MA. That went in tonight and I ran the filter and waterfall pumps for 3 hours. I'll run another test tomorrow morning after the pumps run a few hours but I'm starting to get a little nervous that the PH is not dropping. Any thoughts?

 

[YippeeSkippy]

Hey there David Welcome to TFP

How do you chlorinate the pool?
City or well water?? Can you please run the following panel of tests on your fill water for me (except not the CYA) and give them to us:
FC
pH
TA
CH


It does seem your pH is really high. Did you use PoolMath to determine how much MA to use?
Normally we ask folks to aim for something like 7.6-7.8 when they suspect a really high pH and this allows you to add the MA, circulate and re-test yet protects you from going *too far/too fast*. Then you can repeat as often as needed to go down to pH 7.2 if desired.

Aeration raises pH. The muriatic acid is what lowers the Alkalinity. Water featers, lots of splashing, and such all work to raise pH.

As you lower that Alkalinity, you'll see that the pH won't rise as fast. High TA "pulls" the pH up.

Maddie

 

[AlexPowell]

pH above 8 will show as 8. So you are lowering your pH from somewhere above 8, to something else at 8 or above 8. Just be diligent with the additions

 

[Bperry]

Hello everyone. New to the site. Just purchased a pool that came with a home. ha I've spent a full work week cleaning and trying to understand the pool mechanicals and chemistry. I dropped CYA from 115 to 50 with a partial drains. Water is clear but the Polaris is not doing a good job so I ordered a robot earlier.

FC 1.5
PH 8.1
TA 240
CH175

FC/CH both need to come up, and PH and TA down. Prior to today I was using a test strip that must of been topped out on PH since it always read 8.2. Over the last week my records show I had put in 215 Oz of 31.45% MA and today with the TF-100 kit I found that the PH was still 8.1. Previously with the test strip the TA measured 240 and I got the same thing today with the TF-100 so there has been no apparent change. My goal is to drop the PH to 7.0 and aerate to drop the alkalinity and pool math said 2 more gallons of MA. That went in tonight and I ran the filter and waterfall pumps for 3 hours. I'll run another test tomorrow morning after the pumps run a few hours but I'm starting to get a little nervous that the PH is not dropping. Any thoughts?

How large is your pool? 2 gallons of MA is a lot of acid unless your pool is 50k gallons or more. If you are using the “green” acid, it’s only half strength so make sure it’s really 31.45%.

Also the pool math calculator for pH isn’t very accurate when the change is more than 0.4 so don’t try and calculate a single addition to go from 8.0 to 7.0 cause it’ll be wrong. Just target 7.6-7.8 like mentioned above.

 

[mgtfp]

On top of what Alex said, it can also happen that pH rises back up very quickly while TA is so high. To see the effect on pH after adding acid, you should test pH about 30min after adding acid and mixing it in with the pump running (on fast if you have a VS pump).

Should your pH really be way above 8, you can add enough acid to drop pH from 8.2 to 7.8. Test pH after 30 mins. If still showing as >8, then repeat. Once you have a reading below 8, you can go further down from there.

Edit: Just realised that I must have scrolled past Maddie's post, so I basically repeated that. Ah, well...

 

[cacciato2006]

I input information on my tag but I guess it didn't show. The pool is 30,000 gallons. The label on the acid bottle says 31.45%. The previous owner said he always had trouble keeping the PH down but he didn't say much more than that. I'll test the pool this morning and see where it is. I'll start dosing MA every 30 minutes as suggested until the PH comes down. Once I get the PH down to 7.0 I'll run all the pumps and aerate the pool. How long do you guys think that should take?

 

[cacciato2006]

Maddie, the water is from the local coop. I'll run the tests on the source water this morning and post. Yes I used pool math but I tried to jump to low to0 fast. Rookie mistake. I had added 200+ oz of MA previously using test strips which showed 240. Soon as I got the TF-100 I tested it again and still got the same result. So I updated the app and it said to go from 8.1 PH to 7.0 add the MA. If the PH is too low I can turn on everything and aerate it quickly. I certainly appreciate all input.

 

[cacciato2006]

Liquid chlorine was purchased from Walmart and is 10%. I'm not adding any stabilizer back in.

 

[Bperry]

I input information on my tag but I guess it didn't show. The pool is 30,000 gallons. The label on the acid bottle says 31.45%. The previous owner said he always had trouble keeping the PH down but he didn't say much more than that. I'll test the pool this morning and see where it is. I'll start dosing MA every 30 minutes as suggested until the PH comes down. Once I get the PH down to 7.0 I'll run all the pumps and aerate the pool. How long do you guys think that should take?

Do NOT shoot for 7.0 all in one step. Just get to 7.6-ish. Two gallons of acid in a 30k gallon pool will crash the pH unless it’s ~10. Please check your test procedure to make sure it’s correct. Something doesn’t sound right here. Don’t ever allow the pH to go below 7.0.

The pH will always rise over time that’s probably all the previous owner meant.

 

[cacciato2006]

I'll test as soon as the sun comes up. If the PH has "crashed" do I just aerate aggressively to get it back up or go buy soda ash?

 

[PoolStored]

FC 1.5
PH 8.1
TA 240
CH175

pH rises the fastest when TA is high and/or when pH is low. With a TA in the 200s, you will see pH rise pretty quickly.

PH TA Relationship - Further Reading

www.troublefreepool.com

I'll test as soon as the sun comes up. If the PH has "crashed" do I just aerate aggressively to get it back up or go buy soda ash?

No, use 20 mule team borax
Lower pH - use muriatic....TA also comes down
Raise pH - use borax (20 Mule Team).....it has little effect on TA.
Lower TA - acid and aeration method....see link to lower total alkalinity below
Raise TA - use baking soda....it has little affect on pH

Once I get the PH down to 7.0 I'll run all the pumps and aerate the pool. How long do you guys think that should take?

It depends. The most effective is tons a very tiny bubbles. Takes me 12 hours in a 30K pool to lower TA 10 ppm and return pH to same level. With your TA as high as it is, pH may rise fairly quickly again in the beginning. As your TA comes down, the rise from aeration will slow. Either way you will get there. Shoot for 80 TA to start. You cannot do it in one slug. Lowering your TA will slow the pH rise to something manageable. I keep TA at 60, with SWG. My pH didn't move all season.

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.

www.troublefreepool.com

Here is my rig on a sump pump:

Aerator.jpg

• PoolStored
• Sep 11, 2022

 

[cacciato2006]

So I just tested the tap water and the pool water. As a reminder I added 2 gallons of MA last night.
Tap water: CH 50, Fc 0, PH 8.1, TA 330 and 350. I tested TA twice to verify.
Pool water: CH 175, Tc 1.5, Fc 1.5, PH 7.3, TA 190.

Yes, the Fc was 0, I used a test strip after the titration and it didn't detect any Fc either. We live in a rural poor community and the water system is terrible. Frequent boil water notices. I've contacted the water system operator to come out and check both my properties on that same system.

It would seem with the high TA from the tap I'm going to have to cut in a RO system to ever get it down to a reasonable level.

I've added some liquid 10% chlorine this morning to move the Fc up to 3.0 and then I'll adjust again tomorrow.

CH was 100 several days ago and I put in 25lbs of Calcium and now its 175. I have another 50 lbs. coming which should get me in a better range.

What are your thoughts?
David

 

[PoolStored]

What are your thoughts?

1) Test your CYA and post that number. Have you read through this yet? Link-->FC/CYA Levels You need to chlorinate for your CYA level.
2) Yes, that is a high TA fill water number. Reverse osmosis (RO) is used to reduce Calcium Hardness (CH) and/or CYA in pool water, not clear if it works on TA... @JoyfulNoise @mknauss ?
3) Follow the link I gave you for lowering TA.
4) With the CH of your fill water, starting with CH in the 200-250 range is just fine. This too will rise and the only way to get it out is to replace water or run RO on it.
5) Any pH in the 7s is fine, don't try to raise it, it will raise naturally. Use only Muriatic Acid to lower it.
6) Are you using pool math? Go to the gear in the upper right and click. Scroll to bottom and enable sharing of math logs with TFP. then we can see them.
7) Enable CSI tracking.

 

[cacciato2006]

CYA is 50. Understood on FC/Cya. It was 115 but I did some partial drains to get it down.
My initial reading on RO suggest that it can reduce TA but I'm still reading. If anyone has any input on RO and a system appropriate for pools?
Yes, I'm a subscriber to the pool math app.
According to the app, CSI currently is -0.36 and recommends no lower than -0.30.

 

[mknauss]

I believe RO will remove alkalinity from water. But I doubt you need nor want to pay for a system large enough to provide make up water for your pool. Better is to focus on reducing evaporation and harvesting rain water.

 

[PoolStored]

According to the app, CSI currently is -0.36 and recommends no lower than -0.30.

It is fine for a while in the winter, and is normal. Don't "chase" CSI daily, particularly in the winter. A few days/weeks/months out of range (due to temperature) will not harm your pool.

In the winter, as the temperature goes down, the PH naturally goes up, resulting in the CSI staying at about the same level it starts with. If you are tracking and adjusting PH, you should allow this natural PH increase instead of "correcting" it.

 

[cacciato2006]

I believe RO will remove alkalinity from water. But I doubt you need nor want to pay for a system large enough to provide make up water for your pool. Better is to focus on reducing evaporation and harvesting rain water.

I found a 300 GPD RO system for $600 from Lowes that will produce 30,000 gallons. My evaporation may be just a little more than that per year. I'll have to run the numbers to see how often the filters would need to be changed. Not sure how you would slow evaporation in Texas.

 

[cacciato2006]

It is fine for a while in the winter, and is normal. Don't "chase" CSI daily, particularly in the winter. A few days/weeks/months out of range (due to temperature) will not harm your pool.

In the winter, as the temperature goes down, the PH naturally goes up, resulting in the CSI staying at about the same level it starts with. If you are tracking and adjusting PH, you should allow this natural PH increase instead of "correcting" it.

the feed water has a ph of 8.1 so not much need to raise the pool PH after dosing the pool with MA. Ok on CSI.

 

[pjt]

Where are you in Texas? Update your profile when able.

 

[Bperry]

the feed water has a ph of 8.1 so not much need to raise the pool PH after dosing the pool with MA. Ok on CSI.

The TA will come down for free as you manage the pH to stay in the 7’s.