TA and CYA - what is the proper sequence??

[LisaDLu]

Here are some of my numbers today:
PH - 8.0 (added 16oz of acid).
TA - 50
FC - 6.5
CYA - 50

I am going to add 27 oz of conditioner in a sock to my skimmer tomorrow to raise my CYA from 50 to 70.

I have never had to raise my TA before but to go from 50 to 70 pool math says to add 47oz of baking soda. Can I just use regular old generic baking soda from the store and how to I broadcast into the pool? Do I just sprinkle it all around?

By tomorrow I will probably need more acid (I usually need to add every day due to rising PH) so what is the proper sequence to add acid, conditioner, and baking soda?

Thank you!!

 

[Paul.]

Hi Lisa,

Yes you can add baking soda to increase your TA, but you will have to add more than 47oz. According to pool math, I see 80oz for a 17000 gallon pool.
But you must remember that you will be also adding acid to reduce your pH. Assuming that you add enough to lower you pH from 8.0 to 7.6, you will also be losing another 2.3ppm of TA (assuming 0 borates), which would make it about 93oz.

I also see 45oz of CYA to get from 50 to 70ppm according to pool math, and not the 27oz that you have put.

I assume that the reason that your TA is low is because you are adding a lot of acid to keep your pH stable.

May I ask if you have anything that could possibly raising your pH through aeration? (waterfalls, sprinklers, high returns, high SWG %)

Maybe by eliminating some factors, you will be able to get a more stable TA and therefore pH in the long term.

To answer your question, I would put the CYA in a sock in the skimmer or close to the return, 2) add the acid in the pool, 3) wait an hour, retest TA and add baking soda according to the result.

 

[Catanzaro]

Here are some of my numbers today:
PH - 8.0 (added 16oz of acid).
TA - 50
FC - 6.5
CYA - 50

I am going to add 27 oz of conditioner in a sock to my skimmer tomorrow to raise my CYA from 50 to 70.

I have never had to raise my TA before but to go from 50 to 70 pool math says to add 47oz of baking soda. Can I just use regular old generic baking soda from the store and how to I broadcast into the pool? Do I just sprinkle it all around?

By tomorrow I will probably need more acid (I usually need to add every day due to rising PH) so what is the proper sequence to add acid, conditioner, and baking soda?

Thank you!!

Yes, plain old baking soda. Is your PH @ 8 after adding the acid, or before?

Saw your plaster was done in January of 2015. Your PH rises from what levels and how often? You are adding acid daily? If so, how much daily and what PH level are you at, and what PH level are you trying to get to?

 

[Divin Dave]

Paul has hit the nail on the head exactly.

Just do that and you'll be ok.

 

[Paul.]

Also I see that you have the Taylor K2006 kit, and the pH scale ends at 8.0. In your case, the pH may be well above 8.0. (as was my case when I first started out).
Another experiment that you may also try, is use the Acid demand Test offered in your kit and using the drop test, add the amount of Acid necessary offered in the Table to get the pH down properly.
Then retest and add the Baking soda.


I used this method after having much trouble with high pH. My pH has been stable at 7.6 with a TA of 85 and havent had to add acid in months. My SWG runs at 15% and no problem with chemistry.

 

[LisaDLu]

Thanks everyone! My pools PH is rising due to the curing plaster (my SWG is set at 10%) and I guess all the acid I have to add is the reason my TA has slowly drifted down to 50. I usually have to add acid every day to keep it below 7.8 (I always lower it to about 7.4 or 7.5) and it's raising slower than it did when first plastered in January but I'm still adding acid about 5 days a week if not daily (but smaller amounts now).

I also have a problem with high CH. I was just reading a thread where a person who had high CH was keeping the TA at 50 so they could get their CSI number to be slightly negative to avoid scaling. Now I'm thinking maybe I should just let the TA stay at 50 but at what number is TA a problem and I should I try to raise it? 40 or below?

Numbers from yesterday:
PH - 8.0 (added 16oz of acid).
TA - 50
FC - 6.5
CYA - 50
CH - 575
Salt - 3300
temperature - 90

 

[chem geek]

TA of 50 ppm is fine if other water parameters are higher to have the CSI closer to zero to protect plaster surfaces and avoid scaling. As for a magic number where TA is a problem, it just is increasing risk the lower you go because at some point the pH could drop too quickly if you were to add any net acidic chemicals. On the other hand, with CYA in the water, that provides some additional pH buffering. I wouldn't go below 50 ppm in a pool because it should not be necessary. You probably have minimal carbon dioxide outgassing right now so the pH rise from the plaster is something that will just require acid to compensate.

With your current numbers, if you went to 7.4 in pH the CSI would go to -0.4 while with plaster curing it would be better to keep the CSI higher if possible. Are you sure you are getting scaling in your salt cell with the CSI close to 0? One way to avoid that and also reduce the frequency of acid addition is to use 50 ppm Borates.