Chasing PH

[Glitterbub]

We just took over our pool from the startup company this month. I am having trouble getting my PH down. Wet Edge refers to LSI maintenance for the warranty, so I log in Pool Math and get chemical dosage suggestions there, but also play with the sliders in the Orenda app to make sure I'm in the green LSI range. My goal is to get down to a 7.7 PH. I test with the Taylor block as well as an Apera digital tester. I ran both side by side for a while to make sure I calibrated the Apera correctly.

Readings taken at approximately the same time at night. The additions were above what was recommended by the app. I did this because other additions hadn't resulted in the expected decrease. Usually only 2oz above recommended. CYA is 75, so I figured 5.6 FC is my minimum. I've been slowly bringing the FC up. Purchased the muriatic acid from Lowes. The lowest I've been able to get is 7.8 but it bounced right back. I was at 8.0 yesterday and didn't add anything. Going to test today to see what my "untreated gain" is to try and get ahead of that for the next dose.

Orenda doesn't start alarming until I get up to 8.3, but Wet Edge wants it lower. I think 7.6 is the Wet Edge max, but Wet Edge also wants me to keep the LSI green and I can't do both. Working on getting my calcium up, but didn't want to add that to the mix until I got the PH figured out. One battle at a time.

6/11/2024
FC 5.5
CC 0.5
PH 8.4
TA 70
CH 300
Salt 3200

Added 22oz of 29% muriatic acid.

6/12/2024
FC 6.5
CC 0.5
PH 8.1
TA 70
CH 300
Salt 3200

Added 16oz of 29% muriatic acid

6/13/2024
FC 7.0
CC 0.5
PH 8.0
TA 70
CH 300
Salt 3200

 

[ajw22]

I don't understand what you are trying to do with your acid additions.

22oz of 31% MA will lower pH by 0.3

16oz of 31% MA will lower pH by 0.2

With a pH of 8.4 and you add 22oz of MA your pH becomes about 8.1 right about where it was on 6/12.

Neither MA addition was going to get your pH down to 7.6-7.8.

You should not lower your pH by more then 0.4 at one MA dose. That is about 28oz. Add that MA, wait 30 minutes, retest, then add mode MA until your pH is between 7.6 to 7.8.

It looks like your pH climbs about 0.1 per day which is about normal. So if you test pH and add MA twice a week you will find your pH around 8 and knock it down twice a week.

 

[Glitterbub]

I don't understand what you are trying to do with your acid additions.

Well neither do I. Ha!

I’ve been following the pool math recommended additions. Just now I entered my latest PH result which was 8.3. It only recommends 16 oz to get to 7.7. I verified my pool size is correct in the app.

 

[ajw22]

Standby on explaining what is going on with PoolMath. Watch this thread...

Difference in MA Addition Recommendation?

@Leebo Why are these PM recommendations so different when calculating it with TA or from Effects of Adding? This arose in this thread where 17 oz is not getting close to lowering pH by 0.5. https://www.troublefreepool.com/threads/chasing-ph.296455/post-2594572

www.troublefreepool.com

If the actual results don't agree with the robot then add more or less and get to your actual target. Add more MA and test in 30 minutes until you get to 7.6 - 7.8

 

[AUSpool]

Check that your muriatic acid strength matches what your using in the app.

I wouldn’t go any higher on the CH. There is always calcium in town water supplies so in the absence of overflowing rain your CH will creep up over time.

We would round up that CyA value to 80ppm and then choose your ideal FC target from that.

 

[Glitterbub]

Check that your muriatic acid strength matches what your using in the app.

This is what I’m using.

Added pic to verify pool size.

 

[AUSpool]

Where did the 16oz addition actually move your pH too?

So the simple answer can be ruled out which only leaves every thing else. Testing error, not saying you’re doing anything wrong but there is a lot that can cause variation and it all adds up. The theoretical pH calculations are really quite complex where the difference between the now values and the target value can have a substantial impact. Going from a pH of 8.3 to 7.7 in pH terms is actually quite a large change. And your pool pH is constantly moving.

The best advice I can offer is not to stress over the difference and do as Allen suggests, add the suggested dose, test in half an hour and add a second dose if needed as calculated from a new test. Keeping records or logs will help with future additions.

 

[Glitterbub]

Where did the 16oz addition actually move your pH too?

8.1 to 8.0

So the simple answer can be ruled out which only leaves every thing else. Testing error, not saying you’re doing anything wrong but there is a lot that can cause variation and it all adds up.

Taylor drop based test kit with block and an Apera testing probe. Both correlate and the probe has been calibrated.

The best advice I can offer is not to stress over the difference and do as Allen suggests, add the suggested dose, test in half an hour and add a second dose if needed as calculated from a new test. Keeping records or logs will help with future additions.

Will do. Still don’t understand why the suggestion is so far off. Based on @ajw22 above, the pool moves consistent with the added quantity of MA, just that the app is not calculating enough. Is there an upper limit in the program so that you don’t swing it too hard? Max calc is .4 reduction at a time?

 

[AUSpool]

I’m not saying there’s anything wrong with your testing is more about the entire pH calculation system. It’s complicated. If you’re out by just one drop on the TA the 70ppm becomes an 80ppm and your 16 ounces of acid becomes 18 ounces of acid. And maybe the starting pH was 8.34 or the startup company have used product with borates. It’s just easier to add the 16oz and then another dose to go from 8.0 to 7.7.

You may want to tweak your volume and try 16,500g to see if that works better.

 

[Glitterbub]

I’m not saying there’s anything wrong with your testing is more about the entire pH calculation system. It’s complicated. If you’re out by just one drop on the TA the 70ppm becomes an 80ppm and your 16 ounces of acid becomes 18 ounces of acid. And maybe the starting pH was 8.34 or the startup company have used product with borates. It’s just easier to add the 16oz and then another dose to go from 8.0 to 7.7.

You may want to tweak your volume and try 16,500g to see if that works better.

Fair enough. I'll start getting a little more adventurous.

 

[AUSpool]

Not sure if you’ve realized yet but in pools not using acidic stabilized chlorinating products the pH will constantly be rising. New concrete and plaster pools tend to rise more as they cure. Water features like fountains, spa jets, bubblers and infinity edges etc. also add to pH rise. Adjusting pH is just one of those things we learn to live with. Running TA on the low side can help to reduce the pH rise.

From your results in the first post the combined acid additions should have lowered your TA by 10ppm but it remained stable. I assume there is TA in your fill water. There normally is. It’s a good idea to test your tap water for both TA and CH.

If you go back and have a look at the link from post #4 there is a much better explanation then I can provide as to why the dose’s didn’t match the expected targets.

Difference in MA Addition Recommendation?

@Leebo Why are these PM recommendations so different when calculating it with TA or from Effects of Adding? This arose in this thread where 17 oz is not getting close to lowering pH by 0.5. https://www.troublefreepool.com/threads/chasing-ph.296455/post-2594572

www.troublefreepool.com

I like the The Old PoolMath page (link from pottom of every page). It’s good to play with the levels and see what changes will have on the CSI. I prefer TFP’s CSI and recommended ranges rather then the Orenda one.

Using PoolMath to calculate a 0.4 point change within the 7.8-7.2 range would provide a better dose volume to use to bring you pH down from above 8. I would be adjusting your pH a bit earlier and use your records and regular testing to provide a regular dose.

There are a lot of users that are happy with their Apera meter. You’ve probably already got this from the instructions but it will give best results if the probe is stored wet in a storage solution (normally a potassium chloride solution) and check it’s calibration regularly. You can use one of the calibration solutions as a reference check without a complete recalibration.

 

[Glitterbub]

Updated results. Hottest days of the year so far. Have been bumping up SWG percentage as I watch the FC. Pump basically runs 24/7. Changed from 17% to 20% and now to 25%. Keeping an eye on the CC going from .5 to 0 to 1. We've had a lot of people in the pool yesterday and hot days.

6/14/2024
PH 8.3

6/17/2024
FC 3.0
CC 0.5
PH 8.8
TA 70
CH 300
Salt 3000
Added 28oz 29% Muriatic Acid

6/19/2024
FC 7.0
CC 0.5
PH 8.5
CYA 60
Salt 3200
Added 28oz 29% Muriatic Acid

6/20/2024
FC 6.0
CC 0.5
PH 8.1
Added 28oz 29% Muriatic Acid

6/21/2024
FC 8.0
CC 0
PH 7.8

6/22/2024
FC 6.0
CC 0.0
PH 8.1
TA 60
CH 300
Added 28oz 29% Muriatic Acid

6/23/2024
FC 5.5
CC 1.0
PH 7.5

Adjusting pH is just one of those things we learn to live with. Running TA on the low side can help to reduce the pH rise.

Was prepared for it, just not this often and in this quantity. Hopefully it will slow down with age. Right now it's almost a daily thing.

From your results in the first post the combined acid additions should have lowered your TA by 10ppm but it remained stable. I assume there is TA in your fill water. There normally is. It’s a good idea to test your tap water for both TA and CH.

Great idea, will check.

You’ve probably already got this from the instructions but it will give best results if the probe is stored wet in a storage solution (normally a potassium chloride solution) and check it’s calibration regularly.

Thanks. So far it has been consistent with the block. I was over 8 and wanted to know how far over I was to get a better idea if what I was doing was making any difference.

 

[Sunnydaze]

Something isn't adding up. You added nearly a gallon of 29% acid in 5 days. That would have decreased your TA by close to 30ppm but it's only dropped 10. You're not adding 20ppm in 5 days from fill water. How certain are you of the 16,000 gallon calculation?

 

[Glitterbub]

Something isn't adding up. You added nearly a gallon of 29% acid in 5 days. That would have decreased your TA by close to 30ppm but it's only dropped 10. You're not adding 20ppm in 5 days from fill water. How certain are you of the 16,000 gallon calculation?

That’s what is on my pool paperwork. Going off of memory, I’ll have to look it up tonight dimensions are: 16x34 4/5/4. 7x7 spa takes up half the 7ft tanning ledge.

 

[Glitterbub]

More results, starting from where I left off. LSI and CSI show me in the green, but the manuals for the plaster and the heater want me in the mid/high 7's for PH. Pool paperwork says 16k gallons. Verified the Apera is calibrated using the 7.0 solution. In the window of time we're looking at I've had sod installed around the pool. Ended up with dirt inside of it that the dolphin had to get. Not sure how that impacts these numbers. Pool is clean now.

Aside from the Hayward version, is there some kind of third party device that can automatically add MA? My schedule makes this difficult to do every other night.

I tested my tap water and got TA of 100 and CH of 150.

6/23/2024
FC 5.5
CC 1.0
PH 7.5

6/24/2024
FC 8.0
CC 0
PH 8.3
TA 60

6/25/2024
FC 5.0
CC 0
PH 8.4

6/26/2024
FC 5.0
CC 0
PH 8.4
TA 60
CH 300

Added 28 oz 29% MA

6/27/2024
FC 5.5
CC 0
PH 8.1

Added 28 oz 29% MA

6/29/2024
FC 5.5
CC 0
PH 8.3

Added 28 oz 31.45% MA

6/30/2024
FC 7.0
CC 0
PH 7.8
TA 60
CH 325
Salt 3200

7/2/2024
FC 5.5
CC 0
PH 8.4

Added 28 oz 31.45% MA

7/4/2023
FC 7.5
CC 0
PH 8.2

 

[ajw22]

Aside from the Hayward version, is there some kind of third party device that can automatically add MA? My schedule makes this difficult to do every other night.

You can use a Stenner pump with a timer to add MA.

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