"Adjusted TA" calculation needed for PH stabilization

[Drd]

I have just learned something I hadn't read about here regarding the problem with PH always rising and having to add acid.

I realize the nature of using destabilized chlorine has an effect on PH levels.

I was trying the method of lowing my TA to below recommended levels to stabilize my PH which is not happening. I have been constantly 80 to 90 TA with PH rising daily until it is over 8.0 ppm again. I added acid to get TA down to 60ppm and PH was at 7.2; PH rose the next day to 7.4 so I didn't aerate no point then 7.6 so I have the same problem.

Today, yes I went to buy chlorine and the owner told me that my TA is two low which is what causes PH bounce and that I need to find my "adjusted TA" which is based on how much CYA I have in my pool. This is the first I have heard this except for here about how CYA effects the chlorine and that you need to take that into consideration when testing and maintaining your chlorine levels.

I did some research online and found this other site describing the same thing regarding "Adjusted TA" in detail and instructions on how to test for it Par Pool & Spa: What is Adjusted Total Alkalinity Basically it's dividing your CYA ppm level by 1/3 and deducting that from your TA test to find the "true Adjusted TA level" In my case "before" I lowered my TA per the method taught here, my TA was 80 and CYA 90 so that would mean my Adjust TA was only 50 ppm before I embarked on lowering my TA more, so now with my TA at 60ppm that would mean my adjusted TA is only 30 ppm which is seriously low now.

I subsequently did find a post today on the subject here and the consensus from the ranking members is dismissing this information as having little to no effect. I don't see any adjustments for this on the "The Pool Calculator" either when I enter 8.0 ph, 90 CYA and 80 TA.

I feel confused now and a little disturbed I can not get the same information from everyone.

I can't seem to keep the PH balanced for more than a couple of days which is between 7.4-7.8 and I go through a lot of acid as a result. I don't add Borate due to pets drink from the pool and not willing to go there.

 

[jblizzle]

Are you using PoolMath or the old non-TFP-supported poolcalulator dot com?

I agree there is not reason to worry about the adjusted TA ... and PoolMath should be taking all of this into account.

Have you tried to let the pH stay up around 7.8 - 8? The lower the pH, the faster it will drift up. Lower the TA a little more to 50ppm and then see if the pH will stay around 7.8

 

[Poolzzz]

I think your pool store just sent you down a rabbit hole. ..

Yes total alkalinity is affected by cyanurates and borates but this site's recommendations are based on using TA directly as tested (ie total alkalinity) so follow that. Don't mix units. They've already considered the effects as it's needed.

Really there is no reason to worry about adjusted TA. Just adjust total (ie tested) TA until pH stabilizes.

And I believe Pool Math does consider the effect when it matters which is in the CSI calculation.

 

[Drd]

Are you using PoolMath or the old non-TFP-supported poolcalulator dot com?

I agree there is not reason to worry about the adjusted TA ... and PoolMath should be taking all of this into account.

Have you tried to let the pH stay up around 7.8 - 8? The lower the pH, the faster it will drift up. Lower the TA a little more to 50ppm and then see if the pH will stay around 7.8

I have been using the The Pool Calculator but there seems to be no difference, When I plug in 8.0 ph, 80 TA and 90 cya and calculate it just says add acid as always and I do constantly. Keep in mind I don't know how much over 8.0 I am when testing the only next step is to figure out how much acid to get to 7.4 again. I actually have been adding acid when it gets to 7.8 trying to avoid letting it get over that based on all I have learned.

I also have read that after adding chlorine my ph will be higher than later in the day after the sun and chemical changes have taken place so I might be off just based on when I'm testing??

 

[Drd]

I find the CSI has to many variables involved including water temperature changes that can fluctuate few degrees (this is Arizona) that changes the outcome to use as the way to stabilize ph. If you play with it, it will give you good -/+ results based on combinations in general. But I certainly do look at it.

The one difference I have noticed regarding the two calculators is pool Math doesn't give the "About" on The Pool Calculator information I find very useful to reference. It does mention this site on the bottom of the page so it's kind of confusing why there are two almost identical. Would think there would be a copyright issue.

 

[jblizzle]

The original pool calculator was created by a former Admin of TFP. He sold that calculator off, with stipulation that TFP could still use it. The owners went AWOL for awhile and we wanted to make updates to it ... so we spun off and maintain PoolMath at TFP to keep it up to date.

I think pool calculator was sold again and thus the couple graphical visual changes they have made over the past few years.

What is the "About" information you are referring to? If you mean the information about each parameter, that is all in TFP Pool School: ABCs of Pool Water Chemistry

 

[Leebo]

The Pool Calcultor was built many moons ago by a former TFP Admin when the site was very young. He then sold the code to an App developer who wished to use the code to build an app that reads test strips and gave advice. This App never took off and the company went nowhere.

During the sale of the code TFP kept a license to the code as well which it exercised its right after a year or two of the Pool Calculator not getting updated. For about 5 years the Pool Calculator sat untouched as the owner moved onto other projects while Pool Math evolved into other projects.

Last year or this year the code for Pool Calculator was sold to an investor who’s goals are unknown. They’ve done some updates to make their program look like PoolMath and copied Pool School on their webpage. Pool Calculator has NO affiliation with TFP and I caution those who use it.

 

[tim5055]

I feel confused now and a little disturbed I can not get the same information from everyone.

I can't seem to keep the PH balanced for more than a couple of days which is between 7.4-7.8 and I go through a lot of acid as a result. I don't add Borate due to pets drink from the pool and not willing to go there.

I'm sorry to say that as many web sites you look at will probably have the same number of different ways to do things. Not everyone is going to give the same information.

Because of this do not try to mix advice from one site to another. It's a recipe for disaster.

Like our name implies, we try to make things as trouble free as possible, so PoolMath does all the calculations for you.

So, lets look at some other things. What do you have in the pool creating aeration? Waterfalls, water features, return jets turned up (creating ripples on the surface) bubblers or even a pack of kids and dogs splashing create aeration. Aeration causes pH rise. Any of these things happening?

On my pool the main water return is a wide sheer decent waterfall. Pretty to look at, relaxing ot listen to but it causes pH rise all the time. I keep my tested TA (not adjusted) at 50 and understand I will always be adding acid.

 

[JoyfulNoise]

I’m on the road and can’t answer this thread more deeply but once you get your TA down near 60ppm, your pH should be kept between 7.6-7.8. Only add acid once your pH is above 7.8 and go no lower than 7.6. Going all the way down to 7.2 should only be done when lowering TA. Trying to stabilize a pH below 7.6 is a fool’s errand. You should also be monitoring and tracking your CSI. If you allow your CSI to be too negative (less than -0.3) for too long, you will damage your plaster.

 

[mas985]

Have you tested your fill water to see what you are adding in terms of TA and PH?

 

[Drd]

The original pool calculator was created by a former Admin of TFP. He sold that calculator off, with stipulation that TFP could still use it. The owners went AWOL for awhile and we wanted to make updates to it ... so we spun off and maintain PoolMath at TFP to keep it up to date.

I think pool calculator was sold again and thus the couple graphical visual changes they have made over the past few years.

What is the "About" information you are referring to? If you mean the information about each parameter, that is all in TFP Pool School: ABCs of Pool Water Chemistry

Oh I see, well someone has updated The Pool Calculator lately too. They have a new interface but let you click and see the older one if you like using that one instead. It is handy to have the "about" in each chemical section for easy reference though. I think they came out with an app for the smart phone is what's going on.

 

[Drd]

Have you tested your fill water to see what you are adding in terms of TA and PH?

Interesting that you asked and yes, I did today in fact. Although, I have not added any water after I put acid in to bring TA down to 60ppm (although I do need today we have been in triple digits now and evaporation is on the rise).

City tap water test (using the Taylor 2006C regents):
CH = 140ppm
TA = 100ppm
FC = 0
CC = 1

I do not have any water features aerating the pool. Just the pool pump running at night. No one has used the pool. We have not had any rain in months (I live in Arizona). In fact, I just ran out of chlorine in my feeder before I was able to get to the store and now this is my test today:

FC = 0
CC = 1
TA = 70
PH = over 8.0 did test to see how much acid I needed to add and it was very little to bring it down to 7.4 compared to before???

I thought when chlorine was burnt off, ph lowered but this is the opposite reaction.

 

[Drd]

Interesting that you asked and yes, I did today in fact. Although, I have not added any water after I put acid in to bring TA down to 60ppm (although I do need today we have been in triple digits now and evaporation is on the rise).

City tap water test (using the Taylor 2006C regents):
CH = 140ppm
TA = 100ppm
FC = 0
CC = 1

I do not have any water features aerating the pool. Just the pool pump running at night. No one has used the pool. We have not had any rain in months (I live in Arizona). In fact, I just ran out of chlorine in my feeder before I was able to get to the store and now this is my test today:

FC = 0
CC = 1
TA = 70
PH = over 8.0 did test to see how much acid I needed to add and it was very little to bring it down to 7.4 compared to before???

I thought when chlorine was burnt off, ph lowered but this is the opposite reaction.

Update:
I think I finally get it; I hope anyway: Although PH being balanced is #1 paramount, the TA level is critical to keeping the PH stably balance (from moving) and TA is less important to keep in the range of 80-120 ppm then it is to keep PH in the range of 7.2-7.8 (7.4-7.6 ideal), therefore, TA needs to be given priority over PH adjustments and lowered or raised as needed to effectively keep the PH from moving around, then you adjust the PH accordingly so it is in the balanced range. This should result in the PH remaining stable for longer periods and less acid treatments required. It's just that this is a trial and error type methodology that is such a confusing & frustrating process.

After lowering my TA from 80 to 60 ppm and to PH 7.2 about 4 days ago, my PH is over 8.0 and TA 70 now, so I'll try going down to 50 and then raise the ph to where it should be and wait and see it it stabilizes, then found the problem. But If the PH is even more radical, then I know the problem was the TA was too low all along and I'll work at raising the TA and lowering the PH (which I'm not sure how to do yet) and see if that fixes the problem.

I do have high CH which may be part of the problem I heard.

 

[jblizzle]

Sort of .....

If the TA is VERY low, then pH cold be volatile.
But if you think going from 50ppm to 60ppm is going to make your pH more stable and not rise as fast, that is just not going to happen.

 

[cfherrman]

Use the acid demand test when pH is over 7.8 so you can see what the real pH is.

Ex last time I did it, took 4 drops to lower the pH test to 7.6, the chart said to add 1.15 qts of acid, going into pool math I would need 33 oz of acid to go from 8.2 to 7.6 pH.

 

[Drd]

I agree with a low TA of 60ppm my PH jumped right up and I'm guessing that trying to push my TA real low like this to "stabilize" my ph is not going to work and on top of that my fill water is 100ppm. I am beginning to think my problem was it was too low and it still boggles my mind about the "adjusted TA" too. My TA issues was when my TA was consistently at 80ppm when I was using a lot of acid so maybe I needed to raise it but it never showed up on the calculator to bring it up which I'm finding confusing as heck. Some here said go by the CSI but those results are based on what you enter so it's subjective when your out of balance and you're entering numbers to find the right CSI.

I put a gallon of 12% HASA chlorine (potent stuff) directly into the pool yesterday evening as I had no FC and a couple of yellow spots, which I brushed and filtered all night. This evening the FC is still 3ppm (after 106 degrees today) so it's holding chlorine, the HASA feeder will add more chlorine tonight.

The TA is now up to 80ppm and after I added acid which has brought my pH down to 7.6 so ok for the moment but I'm right back were I was when I was going through acid every couple of days and why I follow the suggestion here to lower my TA to 60 which has not worked. And given my fill water TA is 100pm which I had to add, it's going to be a problematic approach anyway. Now I'm using HASA's more commercial higher concentrated chlorine 12% you buy in refillable containers from a HASA reseller and I don't know what ph problems that might pose either. It's hard to enjoy something that requires so much time and money.

 

[mknauss]

Your fill water TA of 100 is a constant input raising your TA. You are probably near 1" of water evaporation a day.

For this area, your fill water is really pretty nice. Much better than Colorado R water (which is CAP water to you in Phoenix, I assume?)

 

[Drd]

Well the alkalinity and ph are ok but we have very hard water. If I wash off my patio glass table in the sun or let it sit and dry, it leaves very hard water spots and white on mental areas. I have to buy a hose filter to reduce that problem on my outdoor things little try and wash your car. I'm thinking of getting a water softener.

Well anyway, I have done some more research of the "Adjusted TA" chemistry and there really is more to this than I think is being given serious consideration. Where it may be a factor for me is I have high CYA level in my pool and that seems the crux of the matter. Base on this information, when I test for TA and get 80 ppm then factor in the calculation for CYA of 90ppm (deduct 1/3) I'm actually only 50 ppm and why I can't stabilize my PH. This is off of Taylor Technologies website and I would think would be a well respected source:

Cyanuric acid also affects the buffering of pool water. A buffer system is composed of a weak acid and its salt. In pool water containing cyanuric acid, the predominate buffer systems are carbonic acid/bicarbonate and cyanuric acid/cyanurate. The buffer intensity of these buffer systems is both pH- and concentration-dependent. At ideal pH (7.4 to 7.6) and cyanuric acid levels (30 to 50 ppm), the cyanuric acid/cyanurate system will not significantly contribute to the buffering of pool water. However, as the cyanuric acid levels increase, they will have an effect on the total alkalinity test result.
The cyanuric acid/cyanurate system contributes to total alkalinity since total alkalinity is the sum of all titratable alkaline substances and cyanurate is a titratable alkaline substance. Therefore, the total alkalinity titration measures both carbonate and cyanurate alkalinities. This affects water balance calculations because the alkalinity term in the Saturation Index equation is strictly carbonate alkalinity.

For the full report go to https://taylortechnologies.com/en/page/155/role-of-cyanuric-acid-cya

 

[Arizonarob]

I know right now in my pool, my CYA is at 80 and my TA is at 70. I burn through 3 cups per day of 10% chlorine every day, and I loose an inch of water due to evaporation. My PH will hold steady for about a day or 2 at 7.5-7.6, then it will take off for 8 with no aeration going on.
Pool math app wants me to add baking soda to bump my TA up to 80, ( even though it says 70-90 is good) but I haven’t because with it at 70, I seem to at least get a day or 2 not having to add MA to the pool. When it was at 80, it climbed up daily by 2 ppm.
My CH holds steady at 270 but recently it dropped to 260 so I had to add some CH to bump it back up. I’m assuming this happened because my autofill is tapped into my water softener, and as I mentioned, I’m loosing an inch of water a day here in AZ with temps in the triple digits.

Drd, one thing I noticed is in your post you mentioned your FC was 0 and your CC was 1. It looks like you may have something organic living in the pool chewing up your FC. My CC never gets higher then 0.5, and that’s only the day after a full day of pool use with tanning lotions, sweat, etc.
Have you performed a OCLT? I think that is going to reveal something going on in your pool.

 

[jblizzle]

PoolMath does not want you to have to do anything. It is just a calculator and will tell you what you need to add to reach the Target that you specify.