How to properly raise TA??

[onaiR]

Hey guys,

I’m trying to raise my TA from 60 to 90.
Today was my second attempt using baking soda using the Pool Calculator, but TA barely moved.


1st attempt:
On 11/19/2017, pool reading was:

• FC = 10.5
• CC = 0.0
• PH = 7.4
• TA = 70
• CH = 300
• CYA = 45-50

So I added 68oz baking soda to tried to get TA to 90 (18000 gallon pool). I checked the next day, still at TA 70, checked 2&3 days later, still TA 70. Baking soda didn’t do anything on my first attempt.


2nd attempt:
On 12/06/2017, pool reading was:

• FC = 11.5
• CC = 0
• PH = 7.0
• CYA = 45
• TA = 60 (even a little lower now)
• CH = 300

I then added 101oz baking soda in the morning to get to TA 90. I checked at night and it’s showing TA 70. So it went up +10 but with 101 oz baking soda that should’ve raise it to TA 90.


Is there something I’m doing wrong to raise TA?


ps. The reason I like to raise my TA, I noticed that my pH been rising more often. Not sure because it’s colder now or low TA may effecting my pH number.


Any input is appreciated. Thanks guys!!

 

[JamesW]

The pH is going down and the TA isn't rising with additions of bicarb. That suggests that something acidic is being added.

 

[onaiR]

The pH is going down and the TA isn't rising with additions of bicarb. That suggests that something acidic is being added.

Sorry James, I should’ve mentioned that I purposely lowered my pH down before the attempt to raise my TA (before putting in baking soda). I believe Baking soda would increased pH, so I made sure pH is in the low side before putting in baking soda.

pH actually been going up more often/than usual. Thus the reason I think the TA maybe the cause. Not sure if the colder weather can effect pH to rise, but my first thought was due to low TA. (I had +100 TA in the summer and pH didn’t change as much as now)

 

[domct203]

........ The reason I like to raise my TA, I noticed that my pH been dropping more often. Not sure because it’s colder now or low TA may effecting my pH number......

Sorry James, I should’ve mentioned that I purposely lowered my pH down before the attempt to raise my TA (before putting in baking soda). I believe Baking soda would increased pH, so I made sure pH is in the low side before putting in baking soda.

pH actually been going up more often/than usual. Thus the reason I think the TA maybe the cause. Not sure if the colder weather can effect pH to rise, but my first thought was due to low TA. (I had +100 TA in the summer and pH didn’t change as much as now)

Which is it? Is you pH rising or lowering?

Baking soda will have very little effect on pH, in fact, in your 18000 gallon pool, 100oz of baking soda will raise TA about 25ppm, but only raise pH 0.05, something most people would not even detect.

Higher TA will generally cause pH to rise, but all pools are different. My TA is about 80ppm, and my pH remains rock solid at 7.4 even with a SWG. Aerating the water (fountains, water falls, bubblers, etc) will also cause pH to rise.

How do you normally chlorinate the pool? Trichlor tablets are acidic and can cause pH to drop, while SWG's tend to make pH rise.

 

[onaiR]

Sorry for the confusion, the pH tend to RAISE more often now. Thus I think the low TA might be the cause of that swing.

I use liquid chlorine. And yes the pool calculator is showing +30ppm TA for 100oz baking soda for my 18000 gallon pool, but yet it only raised to about +10ppm when I did it.
Im just trying to find out if there is something I'm doing wrong before putting in more baking soda.

 

[AimeeH]

The higher your TA, the more likely your PH is to rise. If you lowered your PH using muratic acid, that is what also dropped your TA.

 

[mknauss]

I would strongly recommend not chasing numbers. Do not add any baking soda. Your TA is fine. Your pH should be between 7.2 and 7.8, so it is fine. If it rises to 8.0, add enough muriatic acid to take it to 7.6. Do not overshoot.

How are you chlorinating? Can you add that to your signature?

Take care.

 

[Demegrad9]

I mostly agree with Marty, stop chasing TA. But according to your 12/6 readings, using Pool Math, I get that your CSI is -0.76. Not terribly outside the -0.6 to 0.6 range, but I would suggest a small pH adjustment with to raise your pH from 7.0 to at least 7.2 but certainly no more than 7.4 with soda ash or borax or aeration to get your pH AND CSI in range since you have a plaster pool. Sounds like your pH tends to rise right now anyway, if it is happening quickly then do as Marty suggest, add nothing and just wait for pH to rise and don't take any action until pH is out of range on the high side.

 

[richierich]

I would leave your TA alone. Mine was 60 the entire summer and my PH never moved from 7.2 the entire summer. I added a little borax to bring my PH to 7.5. My point being is that 60 TA left my PH unchanged. I would not raise TA

 

[duraleigh]

I would agree to leave TA alone. If your pool is happy with TA 70 and your pH is reasonably stable......."don't fix it if it ain't broke"

Now, to your question.....There is no real explanation other than testing error or you are not adding baking soda. The calculated amount of baking soda WILL raise your TA the amount you are targeting.....no ifs, ands, or buts. The science is pretty absolute.

What kit are you using to test? Are the reagents fresh? I know it sounds like a stupid question but you ARE using baking soda....correct?

 

[JamesW]

I think that the poster added acid that wasn't reported.

onaiR, can you confirm if you added acid and how much?

 

[onaiR]

The issue here is the pH rising more than before.
In the summer, my pH never really rise as often as now. I always tried to keep it at around 7.4ppm, I probably added muriatic acid once a month to adjust a bit to get it down to 7.4ppm.
Now its winter, pH its rising more often. My first thought was due to TA. Because my TA now is a lot lower vs in the summer time. (Summer TA = 100, Winter/now = 50-60ppm).
Is it not true that low TA can cause unstable high pH?

pH history:
11/5 = pH 8.0
11/6 = adjusted pH to 7.4
11/19 = pH 7.6
11/24 = pH 7.8
11/25 = adjusted pH to 7.4
12/4 = pH 7.8
12/6 = adjusted to pH 7.4

I do use chlorine bleach for my chlorination and yes I was using baking soda to try to raise my TA.

Is it possible that since its the winter, water is a lot colder now that the pH is likely needed to be maintain more than the summer?

Thanks guys.

 

[JamesW]

Low TA does not cause pH rise. The higher the TA, the higher the carbon dioxide level is at the same pH. Higher carbon dioxide levels cause more pH rise.

Also, the lower the pH, the higher the carbon dioxide level at the same TA. So, lower pH is more unstable than higher pH. A pH of 7.8 is much more stable than a lower pH.

The rule that I find helpful is that if the pH keeps going up, the TA is too high and if the pH keeps going down, the TA is too low.

When you get the TA right, the pH will be stable.

I would target a pH of 7.8 and adjust the TA as needed until the pH remains stable.

 

[mknauss]

Can you put what test kit you are using in your signature?

During the summer you were adding fill water. Now you are adding much less. The chemistry of the fill water has an effect on your readings. What is the TA, pH, and CH of your fill water?

Take care.

 

[JamesW]

Also note that lower water temperature makes the water more aggressive to plaster. If the water is too aggressive, the plaster will dissolve and raise the pH. A higher pH allows for a higher TA and helps reduce plaster dissolution.