TA rising ... what's going on?

joecooler

Well-known member
Jan 13, 2019
139
Longmont, CO
I've had my spa for two years now and have consistently struggled w/keeping the pH in the recommended range ... with a new fill it will be around 7.6, but over time it drifts up and stabilizes around 8-8.2. This is actually perfectly comfortable to soak in, but as I understand it not great for some of the components including my SWG system. With my most recent fill, about 6 weeks ago, my TA started in the 30-40 range and the pH was around 7.6 so I figured I'd leave the TA alone. Now it has drifted up to 50 and the pH is 7.8-8.0. The only thing I've done is add a bit of water (maybe an inch) to replace the water that evaporated off. This is a 420 gallon spa. I'm tempted to try to lower the TA back down to 40 to see if that will pull the pH back down. So my questions are, what is causing my TA to go up (I thought it was supposed to be stable), and is it a good idea to try to lower it to get my pH back into the recommended range?
 

dschlic1

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LifeTime Supporter
Oct 5, 2007
690
Valrico, FL
Do you any type of soap to clean any part of the spa? Soap will increase the TA. Also lowering the pH will also lower your TA somewhat.
 

joecooler

Well-known member
Jan 13, 2019
139
Longmont, CO
Don't use soap at all, even when doing a refill ... just a mild bleach solution to wipe down the shell. I've used a lot of pH decreaser on previous fills and it doesn't seem to last at all .. w/in a day the pH is right back up. Based on what I've read it sounds like I should lower TA instead, no?
 

Dirk

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Nov 12, 2017
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Central California
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Aeration causes pH to rise. If ya gots bubbles, ya gots pH-rise. TA in the 50s sounds quite normal to me, but I'm a pool guy, not a spa guy. @cowboycasey, what do you think? Just keep adjusting pH to normal with acid dosing and leave TA alone?
 
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cowboycasey

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Jul 3, 2013
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Southern OK
every time you use your spa the PH is going to rise... not sure why your TA is rising but you are all over it by adding acid to lower it, it will also lower your TA... My sweet spot was in the upper 40 lower 50 TA..

Are you testing everyday or weekly?
 

joecooler

Well-known member
Jan 13, 2019
139
Longmont, CO
I am just testing weekly. Tempted to add a little acid and see if that brings the TA and pH back down. But also feel like I'm not that far out of the desired pH range so wondering if I should let it drift a bit higher before worrying about it.
 

jseyfert3

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Oct 20, 2017
1,453
Southern WI
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With my most recent fill, about 6 weeks ago, my TA started in the 30-40 range and the pH was around 7.6 so I figured I'd leave the TA alone. Now it has drifted up to 50 and the pH is 7.8-8.0. The only thing I've done is add a bit of water (maybe an inch) to replace the water that evaporated off.
Did you measure the TA of the replacement water? If you're on city water, multiple sources are often used and if so, water parameters change as well as they change the mix of supply sources.

Also, when testing, are you doing the test till the color stops changing, then subtracting the last drop? Total Alkalinity - Trouble Free Pool
 

joecooler

Well-known member
Jan 13, 2019
139
Longmont, CO
I didn't measure the replacement water ... never really occurred to me! And when testing, I go til the color stops changing, but didn't know you are supposed to subtract the last drop. That's not mentioned in the TF-100 instructions. Regardless, since I use the same method when I test, my TA has definitely increased by 10-20.
 
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