Am I doing the TA test wrong?

[MostlyCanuck]

Hi there - first opening a few weeks ago and have been testing TA regularly to get the hang of it using Tf-100.

Earlier on it would read much higher values (160+) and more recently seems to have stabilized around 100ish. My PoolMath logs are online if helpful.

Today as I was testing and I realized that maybe I'm not doing it right. The test says to count drops turning from green to "red". In my case, I dont ever really see "red".

For instance, this morning it took 10 drops to go from green to this pinkish-purple:



and then I kept going to see what happens and with 4 more drops it went from that pinkish-purple above to this bright deep pink:



which of the two colours would you use as your "red" threshold?? I have been using the first (recording TA 100 in this case) but I feel maybe it should be the second (TA 140)?? Perhaps I am a bit colour blind... dunno.

what I find even more confusing is that, although the second picture looks more "red" than the first, which makes me think that is the correct reading, water behaviours suggest the opposite. TFP parameters for my pool for TA are 50-90, which would suggest that with the first (lighter pink) reading of 100 i am close to upper range and about right... and it would indeed seem that way given that my PH seems remarkably stable at around 7.8 without tinkering with it. while if the second (more "red") reading was correct, at 140 my TA would be way out of parameters and too high, and I believe I understand with high TA my PH should naturally drift up (which mine doesnt).

Would love your expert opinion on what's going on here!
Cheers

 

[Texas Splash]

You want the second red - more of a bright Barbie pink to my eyes.

 

[Texas Splash]

So you keep adding R-0009 drops until the color stops changing. Normally Barbie pink.

 

[MostlyCanuck]

You want the second red - more of a bright Barbie pink to my eyes.

alright, my thoughts as well. it does seem "more red" than the first..

to my latter point though, that means my TA is in the 140s rather that the 100s and so way out of the 50-90 range. If that is correct:
- why is my PH stable and not drifting up?
- and (esp keeping in mind PH seems alright) should I actively try to bring TA back into range or leave it be?

 

[Oly]

What is your calculated CSI using Pool Math?
--edit-- I ran your numbers and with a TA of 140 you are only slightly negative so with your equipment I would not mess with it at this point.
You may want to test your fill water for TA to anticipate your trend as you add water going forward.

 

[MostlyCanuck]

What is your calculated CSI using Pool Math?
--edit-- I ran your numbers and with a TA of 140 you are only slightly negative so with your equipment I would not mess with it at this point.
You may want to test your fill water for TA to anticipate your trend as you add water going forward.

I have never monitored CSI before but just run the numbers on PoolMath and it shows as -0.21 which seems ok. I assume that's what you are referring to in your post. I guess I need to learn about CSI - it was something I had ignored until now thinking it wasnt relevant for vinyl... thx for the suggestion

 

[Oly]

Keep your CSI slightly negative for your SWG.
If your fill water TA is high then use pool math to estimate how high your pool water can rise before your CSI rises toward neutral. Move your pH up when you run the numbers and note the change, temperature too.
Have fun.

 

[Deb04]

Is it necessary to keep CSI just slightly negative for SWG Or just negative. Mine is -0.82 and has been in that range all summer.

 

[Oly]

This depends on your pool system, equipment and surface type. Vinyl pools are not affected by a low CSI so you have that going for you.
Do be sure your pH is 7.2 - 8.0 as your heater can be damaged by a low pH.
You can post your recent water test results if you want others to provide a more detailed review or check this out..... What Are My Ideal Pool Levels? - Trouble Free Pool

 

[jseyfert3]

to my latter point though, that means my TA is in the 140s rather that the 100s and so way out of the 50-90 range. If that is correct:
- why is my PH stable and not drifting up?
- and (esp keeping in mind PH seems alright) should I actively try to bring TA back into range or leave it be?

Offgassing is required to raise pH even if the TA is high. The more aeration (via waterfalls, fountains, people splashing, etc) the faster the pH rise. If you have a fairly calm pool, then pH rise should be slow even at your TA levels.

As mentioned, if you have a pH rise in check and your CSI isn't positive, don't worry about it. Just keep adding acid as needed to control pH rise.

 

[Deb04]

I was comfortable with everything, until it was said above that you need to keep the CSI slightly neg for SWG. I don’t call my CSI at -.82 slightly negative.

My current testing is as following:
FC 6.5
pH 7.6
TA 50
CH 150
CYA 50 (Lots of rain recently, which has diluted CYA. Closing in 2 week so not raising CYA at this point)

I almost never have to add acid. I’ve added once this year.

 

[Oly]

You can relax all is well with your pool water.
Slightly negative is a relative term.
Plaster pools owners should be concerned if they have your CSI.
You are in TFP nirvana now, drink it up.

 

[MostlyCanuck]

Offgassing is required to raise pH even if the TA is high. The more aeration (via waterfalls, fountains, people splashing, etc) the faster the pH rise. If you have a fairly calm pool, then pH rise should be slow even at your TA levels.

As mentioned, if you have a pH rise in check and your CSI isn't positive, don't worry about it. Just keep adding acid as needed to control pH rise.

Thank you. Most helpful