New to testing and pH/TA question

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M

Maxx

0
May 25, 2009
8
Well, I got the TFP testing kit for DH last year and he never used it (stubborn cuss!). I pulled it out this month and decided to give it a go, myself :-D I'm a little anxious, since I feel like I have to prove myself (and the kit) to DH, and I'm hoping I'm doing everything okay...

First - are the testing chemicals still good? The kit has been stored away from heat or light in a lower level office that stays cool year round.

Second - assuming that the chems are okay, I'm a little confused about the pH and TA relationship. I thought pH was a measure of where the water was on a scale of acidity to alkalinity. Or are they two separate things (acidity and alkalinity)?

Third - here are the latest test results:
FC - 3
CC - 1.5
pH - 6.8
TA - 140
CYA - 30 (it was between 30 and 40, slightly closer to 30)

According to these compared to yesterday's testing, the pH has dropped from 7.2 and the TA has dropped from 170. Does that make sense? To me, the TA drop seems significant, but what would do that? Testing error? I'm also confused that they both dropped at the same time because I thought they would move opposite of each other - if one goes down, the other should go up.

I'm not sure what to work on next and would appreciate any feedback. I think the CYA is okay - we have the popular 'filled sock by the skimmer' that's been dissolving for the past few days. DH is going to put in some bleach tonight (it was a 90 degree sunny day, so I think that's where we lost some FC - it was 5 last night.

If it helps to know this, the day before yesterday, I did an overnight FC loss test and it dropped by 1. I think that's okay, yes? Or not?

DH is jonesing to shock the pool - he said he 'always' does that around this point in pool opening. Not sure if that's indicated by any of the results, though, so I'm holding him off for now. The water is a little cloudy, but there's no visible algae or anything off color. DH had put in a few bucketfuls of semi-dissolved stabilizer at the beginning of the week, so I wasn't sure if that could be still dissolving. We've vacuumed so there's no dirt or anything in the pool, and DH has cleaned the filters several times (the filters are old and tend to clog with all the vacuumed silt) and soaked them in dishwasher detergent just a few days ago.

Thanks so much for any advice or information you can share! I'm officially taking over as Chief Water Tester and Chemical Counsel for our pool :lol: I'm starting a log of all pool related information and activity so whatever info I get, you can trust I will be taking notes and hopefully learning so I don't have to ask the same stupid question twice! :lol:
 
Maxx said:
According to these compared to yesterday's testing, the pH has dropped from 7.2 and the TA has dropped from 170. Does that make sense? To me, the TA drop seems significant, but what would do that? Testing error? I'm also confused that they both dropped at the same time because I thought they would move opposite of each other - if one goes down, the other should go up.:
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Have you, or your husband, added anything besides CYA to the pool? Otherwise, my vote would be testing error. pH will look different depending on the light and the background. Use white. Even off-white will affect your perception; my house is beige and it does affect the test.
 
No - I had him hold off on his nightly chlorine dumpage last night so I could double-check the overnight loss, so there's nothing extra added except whatever additional stabilizer dissolved out of the sock. We did have the filter running with dichlor tablets during the day today - would that have done it?

I'm actually more confident about the pH change than the TA change - the color was definitely lighter tonight. The TA (as tested by the pool store) was high last week and DH was told to add a lot of mur. acid, but that wouldnt have a delayed effect, would it?
 
Maxx said:
No - I had him hold off on his nightly chlorine dumpage last night so I could double-check the overnight loss, so there's nothing extra added except whatever additional stabilizer dissolved out of the sock. We did have the filter running with dichlor tablets during the day today - would that have done it?

I'm actually more confident about the pH change than the TA change - the color was definitely lighter tonight. The TA (as tested by the pool store) was high last week and DH was told to add a lot of mur. acid, but that wouldnt have a delayed effect, would it?
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You can't really run the overnight drop test if there's dichlor tablets in the water somewhere, adding Chlorine.

Go run the tests again. You have the TF100, so there's plenty of reagents. I've lost count of how many times I've lost count of drops and had to dump it and start over.
 
Ack! I hate to stretch your patience...

Between the time I took the first sample and the time you told me to retest, DH added some "pH increase" (not sure exactly what it is - from the pool store).

ETA - it was about an hour and half between that addition and my testing, below

When I retested, here's what we've got:

pH - 7.2
TA - 120 I retested this one three times - would this really drop that much from pH increase chemicals?
FC - 3

I think we need to add some bleach, though I'm just aiming for 4-5, not shock levels. Or do you think we ought to cut DH loose on shocking? When I mentioned the overnight test, the filter was not on until after I took the water sample. Would having the tablets in there, even without the water filtering through, affect the test?

Thanks so much!!
 
pH and TA almost always track together. If you add a pH increaser, your TA will surely go up. If you want to increase your pH without increasing your TA, you should try aerating your pool. I like to just point the return eyeball up so it gushes above the surface. After 24 hours I get maybe a 0.2 to 0.3 increase in pH. As far as the chlorine goes, you'll want to do at least some breakpoint chlorination to get the CC down to 0. If both the pH and TA truly went down, it would seem like it would have to be due to an acid addition, maybe rain water? But you did mention it was sunny, so that doesn't seem likely.
 
As FPM said, go ahead and give DH his moment! Though we all know it's really your moment. ;)

If the tests you're comparing contain anything from the pool store then disregard those. Trust your own testing. The only issue reported about the TF tests is with static affecting the TA test but that shows up as unexpected high results.

Just to check your process, Read the excellent Water Testing Instructions on One Page tutorial.
 
Just recieved my TF100 kit and will be doing my own testing for the first time ... asside from using the strips! Are the results from the Tf100 accurate .. at least compared to the pool store? It's got to be better than the strips. Hoping to Not have to return to the pool store for a long time and wait in line for a test !!
 

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If my PH is low, should I airate my water with a fountain that attaches to my return line and sits in the middle of the pool .. before adding Borax? will I get a .4 or .5 rise over 24 hrs? If I am at 6.9 and want to get above 7.2?
 
Wrenching this thread back onto the original topic...
Maxx said:
First - are the testing chemicals still good? The kit has been stored away from heat or light in a lower level office that stays cool year round.
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They're fine. Sounds like optimal storage conditions. Typically they'd be okay for a year, probably two.
Maxx said:
Second - assuming that the chems are okay, I'm a little confused about the pH and TA relationship. I thought pH was a measure of where the water was on a scale of acidity to alkalinity. Or are they two separate things (acidity and alkalinity)?
Click to expand...
TA is really a measure of dissolved carbonates; pH is the net acid/base balance of everything in the water.
Maxx said:
the pH has dropped from 7.2 and the TA has dropped from 170. Does that make sense?
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Because you are adding CYA, yes it does. CYA is acidic, which will lower pH, and I expect it can also lower TA some (even though the Pool Calculator doesn't show that effect).
Maxx said:
I'm also confused that they both dropped at the same time because I thought they would move opposite of each other - if one goes down, the other should go up.
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No, actually they would move in the same direction; alkalines (bases) will increase pH, acids will lower both pH and TA.

If we didn't cover all the questions, post back and ask them again.
--paulr

P.S. I am not a chemistry expert and my layman's understanding may be technically flawed; however as a practical matter, the water does behave like I said above.
 
Thanks all, especially for the pH TA info - I'll copy to my notes for future reference. I did tell DH that he could shock away with my blessing, but the process was interrupted by a small family emergency.

In the meantime, he did get one large chlorine load in and the pool was up to shock level, but then we weren't around to keep testing and adding, so it's back to this:

FC = 2 (evening reading after a full day of bright sun and 80+ degree temps)
CC = 1.5
pH = 7.0
CYA = 45

He's busy adding chorine tonight and hopefully we'll be able to get back on track. The water is clean, just slightly cloudy at the bottom of the deep end - I'm guessing that the cloudiness was the stabilizer that hadn't dissolved, since it's disappearing as the CYA level came up and the sock dispenser has emptied.

Off I go to re-read the shock lesson, and then I'll hit the testing info. I'm not confident about my chlorine testing abilities and determining when it's 'clear' vs. a faint tint of pink. I did it about 6 times tonight just to be sure...

Thanks again - I'll post back if anything else comes up.
 
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