TA & Temp

[atxjmy512]

Does water temperature play any role in raising or lowering TA?

Prior to this cold snap, my Ta was around 70 or 80 with water temps in the low 60s. Now that my water temp is around 40°, my TA seems to have dropped to around 40 or 50, but I’ve added no chemicals to accomplish that.

Before I start dumping boxes of baking soda in, I’m wondering whether colder water temps bring TA down or at lest fool my tests.

 

[ajw22]

Your pool log show a pH of 8 and TA of 60. That is fine. Don’t begin dumping baking soda in.

A low TA does not require immediate action if your pH is high and stable.

 

[atxjmy512]

Your pool log show a pH of 8 and TA of 60. That is fine. Don’t begin dumping baking soda in.

A low TA does not require immediate action if your pH is high and stable.

I haven’t and won’t. But two caveats - 1) it was probably 50, it was reddish at 50, but turned magenta at 60; 2) my ph tester only goes to 8, so I don’t know that it was exactly 8, it was likely higher.

My question has less to do with what should i do about 50 or 60 and more what should I expect in terms of TA when the water warms back up next week.

 

[ajw22]

I haven’t and won’t. But two caveats - 1) it was probably 50, it was reddish at 50, but turned magenta at 60; 2) my ph tester only goes to 8, so I don’t know that it was exactly 8, it was likely higher.

One drop difference is within normal testing error variance.

My question has less to do with what should i do about 50 or 60 and more what should I expect in terms of TA when the water warms back up next week.

Cold water should not effect TA. Your results are within normal margins of error.

 

[Gary Davis]

The saturation index is greatly affected by temperature, and the chlorine activity is also affected somewhat by temperature.

• But TA?

The wiki for TA on this web site (see above link) doesn't even mention the word temperature (or degrees).

While ALL chemical tests are affected by temperature, if the TA level dropped, I'd first repeat the test under controlled conditions.
If the TA is still dropping, I'd suspect dilution (or maybe someone is adding acid somehow?).

Has it been raining recently?

 

[atxjmy512]

The saturation index is greatly affected by temperature, and the chlorine activity is also affected somewhat by temperature.

But TA?

The wiki for TA on this web site (see above link) doesn't even mention the word temperature (or degrees).

While ALL chemical tests are affected by temperature, if the TA level dropped, I'd first repeat the test under controlled conditions.
If the TA is still dropping, I'd suspect dilution (or maybe someone is adding acid somehow?).

Has it been raining recently?

No rain that I can recall.

Saturation index is the underlying question. At 42°, a 7.8 - 8.0 pH, and my CH level - 10 points of TA can vary my CSI pretty greatly. At 50 TA - my csi is -0.29; at 60 it’s -0.08.

All that said - as was pointed out, I’m within the margin of error and I’m not gonna start dumping boxes of baking soda just yet. Water temps will be a good 10 degrees warmer by Tuesday.

 

[ajw22]

How Cold Temperatures Affect Your Pool/Spa Water

For example, it may take a few more drops of reagent in a total alkalinity or calcium hardness drop test before you see the color change, which will result in a false-high reading.

As a general guideline, we recommend not testing pool/spa water samples that are <45°F (7.2°C).

So, what’s the “get around”? If you must test pool/spa water <45°F (7.2°C), collect the sample from 18″ below the surface (again…brrrrrrr!) in an opaque container, bring it inside to a warmer environment, and wait a few minutes before performing the test. Remember…patience is a virtue!

 

[jimbethesda]

I live in Austin too. On Dec 19th, we received about 1.5 inches of rain at our house. I looked at your logs. On Dec 17, your TA was 70 and on Dec 23 it was 60. Your TA drop is likely due to rainfall, and also due to the margin of error with the test itself.

 

[atxjmy512]

How Cold Temperatures Affect Your Pool/Spa Water

For example, it may take a few more drops of reagent in a total alkalinity or calcium hardness drop test before you see the color change, which will result in a false-high reading.

As a general guideline, we recommend not testing pool/spa water samples that are <45°F (7.2°C).

So, what’s the “get around”? If you must test pool/spa water <45°F (7.2°C), collect the sample from 18″ below the surface (again…brrrrrrr!) in an opaque container, bring it inside to a warmer environment, and wait a few minutes before performing the test. Remember…patience is a virtue!

I live in Austin too. On Dec 19th, we received about 1.5 inches of rain at our house. I looked at your logs. On Dec 17, your TA was 70 and on Dec 23 it was 60. Your TA drop is likely due to rainfall, and also due to the margin of error with the test itself.

I don’t think we got that much but maybe. It’s been a long week.

 

[Gary Davis]

No rain that I can recall.

Dilution (or acid) would have been my first guess, but also what @aj22 said is possible (which is the test is affected by the temperature).
Both greatly affect the TA and rain water, in a way, gives you both:

• Rain water is acidic (although nothing like muriatic acid of course)
• Rain water has zero TA
• Rain water has zero CH

Saturation index is the underlying question.

Personally, I try to keep my CH at about 3 (or even 4) times the TA - when I'm adjusting my CSI - but that ratio isn't the magic - it's just a rough ratio because of the fact calcium doesn't affect much else other than the CSI while TA does affect the pH equilibria a lot (which affects other things).

At 42°, a 7.8 - 8.0 pH, and my CH level - 10 points of TA can vary my CSI pretty greatly. At 50 TA - my csi is -0.29; at 60 it’s -0.08.

All that said - as was pointed out, I’m within the margin of error and I’m not gonna start dumping boxes of baking soda just yet. Water temps will be a good 10 degrees warmer by Tuesday.

You do what you want to your pool where my kind hearted suggestion is to modify something other than the TA (if the TA is within an acceptable range, of course) when you're trying to adjust CSI, where that "something other" is usually CH for a bunch of reasons, at least in my book, such as

• CH doesn't affect too many other things
• CH is cheap to add (Snow Joe is easy to get)
• CH, once set, is pretty stable (unless diluted)