Low TA, high pH

[HappyBubbles]

I use ma to lower my TA and get pH in check and have done so relatively well in the past. But I just purged and refilled the spa, lowered TA and have a problem. I thought something was wrong with my test kit because TA was getting really low but pH just was not cooperating. According to a store test TA is 44 and pH is 8.1. These numbers defy my understanding of TA/Ph balancing and past experience. Should I dump the water and try again? Why is TA not pulling down the pH?

 

[Bperry]

Why is TA not pulling down the pH?

Because it’s a store test. They don’t report TA accurately as it’s adjusted TA. It’s why TFP only values results from one of the two Taylor kits.

 

[proavia]

Post a full set of current test results from one of the recommended test kits.
Test Kits Compared

 

[HappyBubbles]

I redid my own test using my Taylor kit and these are my results:

TA: ~45
pH: >8 (the pink is very light, but it's just not orange enough to match the scale between 7-8 on the test)

 

[proavia]

What test kit are you using?
How old are the reagents?

 

[HappyBubbles]

2 years old

 

[proavia]

What EXACT test kit?

You should replace 2 year old reagents - even if you store the test kit indoors.

 

[HappyBubbles]

Strong feelings and opinions about store tests and which exact Taylor test kit I am using aside, if my reagents are too old to be useful I won't use them anymore.

I still have questions about low TA and high pH though. It's my understanding that to bring pH into the desired zone (7.4-7.6) I need to lower TA (my fill water is TA 250). I did that successfully with TA around 65 before no problem. How can I raise TA and lower pH? Is it not the case that all we can do to directly affect pH is raise it using aeration and we can only indirectly lower it by lowering TA?

I can appreciate that you only accept test results from your recommended kits. But I would also appreciate any advice on this situation if anyone is willing to entertain the idea.

 

[Bperry]

Strong feelings and opinions about store tests and which exact Taylor test kit I am using aside, if my reagents are too old to be useful I won't use them anymore.

I still have questions about low TA and high pH though. It's my understanding that to bring pH into the desired zone (7.4-7.6) I need to lower TA (my fill water is TA 250). I did that successfully with TA around 65 before no problem. How can I raise TA and lower pH? Is it not the case that all we can do to directly affect pH is raise it using aeration and we can only indirectly lower it by lowering TA?

I can appreciate that you only accept test results from your recommended kits. But I would also appreciate any advice on this situation if anyone is willing to entertain the idea.

The desired zone for pH is anywhere from 7.0 to 7.8. All of those values are equally good.

The only reason to mess with TA (the pool store many times doesn’t provide TA, only ATA adjusted total alkalinity) is to keep the pH stable. High TA values cause the pH to rise very fast and low TA values slow the rise down. But if the TA gets below ~50ppm, the pH can tank too low and become acidic.

The TA does not prevent you from adjusting the pH.

 

[HappyBubbles]

The desired zone for pH is anywhere from 7.0 to 7.8. All of those values are equally good.

The only reason to mess with TA (the pool store many times doesn’t provide TA, only ATA adjusted total alkalinity) is to keep the pH stable. High TA values cause the pH to rise very fast and low TA values slow the rise down. But if the TA gets below ~50ppm, the pH can tank too low and become acidic.

The TA does not prevent you from adjusting the pH.

So how do I lower pH and raise TA?

 

[Bperry]

So how do I lower pH and raise TA?

Adding muriatic acid lowers pH. You should ignore TA as long as it’s above 50ppm.

 

[HappyBubbles]

Adding muriatic acid lowers pH. You should ignore TA as long as it’s above 50ppm.

My TA is 45

 

[Bperry]

My TA is 45

Is the 45 from a pool store test? If it is, it’s likely not accurate as explained in the earlier comments. They underreport TA by giving you adjusted alkalinity.

Baking soda raises TA.

 

[HappyBubbles]

Raise TA with soda, lower pH with ma. Keep doing it until they are both right. Gotcha!

Just curious - what is the margin of error with a pool store test compared to the accuracy of a visual colour comparison of the Taylor drop test?

 

[Bperry]

Raise TA with soda, lower pH with ma. Keep doing it until they are both right. Gotcha!

Just curious - what is the margin of error with a pool store test compared to the accuracy of a visual colour comparison of the Taylor drop test?

There’s no way to tell margin of error. Depends on who does the test, whether they cleaned the machine after the last use, had it calibrated on schedule, etc.

The Taylor kits don’t use color comparisons except for pH. Any pH that starts with 7 is just fine.

 

[pjt]

Keep doing it until they are both right.

No. Don't add any baking soda.

You don't need to increase your TA. TA of 50 or above is perfectly fine.

Adding baking soda would increase your TA. MA would lower your TA. It's like pressing the gas and brake pedals at the same time.

What exact kit are you using?

 

[Bperry]

No. Don't add any baking soda.

You don't need to increase your TA. TA of 50 or above is perfectly fine.

Adding baking soda would increase your TA. MA would lower your TA. It's like pressing the gas and brake pedals at the same time.

What exact kit are you using?

The TA from pool store says 45.

 

[Mdragger88]

First- let the spa rest & when the water is still & has been still a little bit retest ph & ta.
If ta is still below 50 add 10ppm worth of baking soda- be careful to not add too much.
Afterwards only lower ph to the high 7’s so you don’t risk lowering ta too far.
Some spas do fine with ta of 40 & some experience ph bounce when it is that low.

As mentioned- order new reagents & be sure they are the correct ones for your comparator.

 

[proavia]

I can appreciate that you only accept test results from your recommended kits. But I would also appreciate any advice on this situation if anyone is willing to entertain the idea.

We don't offer advice based on suspect test results.
And we still don't know what exact test kit you are using - whether the reagents are old or new, list the test kit you are using..

 

[pjt]

The TA from pool store says 45.

Most likely adjusted alkalinity and can't be trusted anyways. OP needs a real test kit.