Daily Testing - pH Won't Drop

[ATXpoolnewb]

Hello,

After recently completing my first SLAM I have begun daily testing for the first time using the TFP protocol. On the first day I ran all the tests and here were the results:

FC - above 5
pH - high, the test kit only goes up to 8.2
CH - 450 - on the money
TA - 90 - goal for my pool was 70

I entered the pH and TA numbers into the Pool Math app and it had me add 9.4 oz of the 31.45% - 20% Baume Muriatic Acid, which I'm pretty sure mine is, attaching a photo to confirm. Since then, I've been daily testing and adding liquid chlorine based on my FC readings (which are really hard to differentiate for me using the pH/FC daily testing dual tower test kit but I think I'm getting it). The pH reading has remained high every day but I haven't been putting anything in for the TA reading, assuming that it had gone done after the 9.4 oz on day 1. When I put 8.2 into the app it's only telling me to put in like 1.1 oz of the 31.45/20 Muriatic Acid.

Any feedback on my process? Am I doing anything wrong?

Thank you!

 

[ajw22]

Are you measuring FC with the R-0870/0871 FAS/DPD test? You should have an actual value not “above 5”.

Are you measuring pH 30 minutes after you add the acid to lower it?

 

[ATXpoolnewb]

Are you measuring FC with the R-0870/0871 FAS/DPD test? You should have an actual value not “above 5”.

No, I'm using the dual Cl/pH tower thing that I thought I was supposed to be using for daily testing. I thought the 0870/0871 was for weekly testing.

Are you measuring pH 30 minutes after you add the acid to lower it?

No, but I will now start doing this. Again, all of the guidance that I received in another thread I posted and on the Pool School page seems to indicate that we're just testing once per day.

 

[Newdude]

No, I'm using the dual Cl/pH tower thing that I thought I was supposed to be using for daily testing. I thought the 0870/0871 was for weekly testing.

That's for down the road once you're at one with the pool and already know what it'll say. It'll say you have a FC level that's likely above min and it will confirm your gut.

seems to indicate that we're just testing once per day.

Under normal circumstances. When things don't go to plan you need to test after the dose to ensure you hit your target(s). That extra test will help answer why it's going south.

 

[ajw22]

No, I'm using the dual Cl/pH tower thing that I thought I was supposed to be using for daily testing. I thought the 0870/0871 was for weekly testing.

The tower thing just tells you if you have chlorine in the pool or not. You cannot accurately judge how much chlorine you have.

Use the FAS/DPD test anytime you want to know your actual FC level to plug into PoolMath and for any chemical adjustments.

The pH test is not valid when FC is over 10 so we need to know accurately how high your FC is.

No, but I will now start doing this. Again, all of the guidance that I received in another thread I posted and on the Pool School page seems to indicate that we're just testing once per day.

By the time you retest your pH has risen. If you want to confirm the accuracy of your chemical addition you need to retest shortly after you added the chemical.

 

[ATXpoolnewb]

Much appreciated y'all!

One additional question - is there any reason to re-test CYA post-SLAM? I have not done that yet.

 

[ajw22]

One additional question - is there any reason to re-test CYA post-SLAM? I have not done that yet.

Test your CYA at least monthly. Maybe every 2 weeks when the pool water is above 85F as CYA will degrade with hot water.

If you are finding that when you test you get the same result you can extend the time between tests.

When you find the test results are changing then you may want to test more often.

Adjust your testing schedule to the rhythm of your environment.

 

[Newdude]

is there any reason to re-test CYA post-SLAM?

Not with a cart filter. With DE or sand they lose water backwashing and the 0 CYA (re)fill water dilutes what's left.

You'll only lose CYA to rain overflow and a little to UV degradation.

 

[ATXpoolnewb]

Thanks to everyone for their advice! I really appreciate it. Here's how my testing went this morning:

FC was at 2 using the FAS/DPD test. pH was high (pink). I input 8.2 into Pool Math and added 4 oz. of Muriatic Acid. 30 minutes later, I tested again and it dropped to 7.8. At that point I added the 31 oz. of liquid chlorine to get my FC level up to 4 per Pool Math. 2 hours later I tested both again and FC was 5.0 and pH was back to the pink/purple color so high.

Any thoughts on these results?

 

[ajw22]

Your pH is 7.8 after adding the acid.

Don't test pH after adding chlorine.

Adding liquid chlorine to water can cause a temporary increase in pH which is usually offset by the chlorine reacting with organics and biological matter which are acidic (creates a proton) reactions. Thus, on balance, the net chlorine reactions are pH neutral.

PH - Further Reading

www.troublefreepool.com

 

[ATXpoolnewb]

Okay thank you. Sounds like I'm on the right track then. Last question (I think). Should I re-test TA? I haven't since the initial reading I took (90 with goal of 70) but I know that it is input in Pool Math on the pH test page so perhaps I should have been re-testing to ensure my initial adjustments resulted in the reduction to target level.

 

[PoolStored]

Should I re-test TA?

Yes.

 

[ajw22]

You should test TA anytime your pH needs acid.

 

[ATXpoolnewb]

Just a quick update on my tests from this morning. Only question I have is when does a pH test gain back validity after added liquid chlorine?

9am
FC = 1.0
pH = 8.2
TA = 100
-added 10 oz. muriatic acid

9:30am
pH = 7.8
TA = 90
-added 4 oz. muriatic acid to reduce TA

9:40am
-added 47 oz. liquid chlorine

Had to go to work so couldn't test again and obviously needed to get the chlorine in before I left.

 

[PoolStored]

Only question I have is when does a pH test gain back validity after added liquid chlorine?

pH test is valid when FC >10

 

[ATXpoolnewb]

Don't test pH after adding chlorine.

Adding liquid chlorine to water can cause a temporary increase in pH which is usually offset by the chlorine reacting with organics and biological matter which are acidic (creates a proton) reactions. Thus, on balance, the net chlorine reactions are pH neutral.

I was referring to this. Like does it make sense to test pH again this evening or just wait until tomorrow morning?

 

[proavia]

Test again this evening