Are we making TA overly complex?

[duraleigh]

Good morning,

I would like help in understanding more about TA. In the old PF days, TA was pretty easy to deal with in that we suggested 80-120. Even then, if you exceeded these norms by a reasonable amount, say 60-160, it was not a big deal.

I know that JohnT successfully runs his pool at a very high TA (about 180, I think) because his fill water is well over 200. My TA in my fill water is 70-80 and I pay no attention to it.

Now, it seems we have developed different levels of TA depending on the chlorination device. I know the science behind it is valid but I am concerned we are overthinking the issue somewhat.

To those of you who have refined our suggested TA levels (Richard, Jason, Evan), could you help us laypersons understand that a little better? I suppose I am OK with the recommendation but I guarantee few here on the forum really understand it.

Please use short words and type v-e-r-y slowly so even I can understand it. :lol: :lol:

 

[JasonLion]

In a simple vinyl liner or fiberglass pool, without a SWG or any water features, the TA level is not all that important. TA levels anywhere from about 50 to over 200 will all work acceptably. Every now and then, particularly after it rains or a large crowd of kids plays in the pool, the PH might drift, but this tends to be uncommon and is fairly easy to correct.

In other situations, with a SWG, fountain, waterfall, or a negative edge, the traditional TA levels, or at least the higher end of the traditional range, cause the PH to rise constantly. This constant upward PH drift gets annoying and also often results in the PH getting way too high, which then leads to metal stains and calcium scaling.

The dramatic increase in the number of SWGs installed in the last several years has make the upward PH drift problem far more common. Also, the detailed understanding of how high TA leads to the PH drifting up was not developed until a couple of years ago. The greater frequency of PH drift problems, combined with this new, more detailed understanding about how to avoid, or at least reduce, the amount of drift, has pushed us to change the general recommendations for everyone.

The change in the recommended levels to include using lower TA levels to control PH drift is quite new. Some of the ideas behind it have been around for some time, but this issue has only risen to the level of changing the generally recommended levels in the last two or three years. Because the current form of the recommended levels chart is fairly new, we may not yet have found the ideal way to explain it to people.

Another factor that has affected this issue is the balance between offering a single set of recommendations that kind of sort of maybe work for everyone vs. customizing the recommendations based on some amount of detail about the specific pool. If you offer a single set of recommendations, you need to use fairly wide ranges on the individual numbers and there will always be some combination of values, all of which are within the recommended ranges, that are in fact unacceptable for a specific pool.

Last year, I started really pushing for splitting the recommendations up based on the answers to a couple of simple questions about the pool, notably what kind of surface it has and what source of chlorine is being used. This allowed us to give recommended levels that ought to actually work with any combination of levels within the specified ranges. I think the idea of splitting the recommended levels table up has worked out well. Still, this approach is quite new and it could turn out to be a mistake, or need some refinement.

I think it is important to realize that even with the split up table there are still many pools that are in situations that are not covered and for which the standard recommendations do not work. The obvious example is people in arid areas with high TA and high CH fill water. There are also several other situations that are not well covered by our current default advice. The simpler you make your default recommendations, the more pools there are for which the recommended levels simply will not work.

There needs to be some balance between keeping the recommendations simple and helping a few people a great deal, vs adding some complexity to the recommendations and thus helping many more people even though each of them needs to do a little more work to follow what you are saying. I don't think that our current system is idea. I am sure it could use a great deal of work. But I am confident that it is an improvement over the old system of a single set of recommendations that used fairly wide ranges and left plenty of room for people to get into trouble even though they were staying within the recommended ranges.

 

[duraleigh]

There needs to be some balance between keeping the recommendations simple and helping a few people a great deal, vs adding some complexity to the recommendations and thus helping many more people

What percentage of pools will operate just fine with a TA of say 70-140? My guess is 90%+. I realize that is simply an anecdotal guess but I think I'm close. I would much rather help those 90% with that general recommendation than try to address the remaining 10% with additional, often confusing, information. I'll say it again.....a significant portion of our newbies (and we do want newbies)do not understand the function of CL and that it is a consumable. I think it is confusing for a newbie to read a suggested TA of 70 in one thread and then 120 in another.

On a somewhat different note, if I remember correctly from a post by Richard, The lower TA does not reduce the overall consumption of acid but, rather, the frequency with which it needs to be added. If that is correct, I need more help understanding that.

To everyone else.....This is an important topic to TFP and I would hope that many of you frequent responders will chime in with your thoughts. There is no "correct" answer but rather a collective opinion that will guide the direction of the forum.

Thanks! :lol:

 

[JasonLion]

What percentage of pools will operate just fine with a TA of say 70-140? My guess is 90%+.

My guess is that this was true 10 years ago, but is no longer true now. There was a poll here a while back that showed that around 50% of TFP users have a SWG. I believe that nearly anyone with a SWG will have problems with PH drift when TA is over 100, and many SWG users will have have problems with PH drift even at somewhat lower TA levels.

 

[duraleigh]

Hey, again, Jason,

(Jason and I know each others thoughts on this pretty well. I'm hoping to get input from many others on the forum :-D )

So, does keeping the TA lower result in less total acid consumption?

 

[Guest]

What percentage of pools will operate just fine with a TA of say 70-140? My guess is 90%+.


Where you put the TA depends on whether you are using unstabilized or stabilized chlorine, gas chlorine, and bromine.
In CPI courses the ASPI recommended ranges for TA for unstabilized chlorine (and this includes SWGs,which produce sodium hypochlorite)are 80-100 and stabilized chlorine, gas chlorine, and bromine are 100-120 and this has been true for a number of years now.
This is because higher TA will cause pH to rise and it offsets the acidic effect of both trichlor and dichlor, chlorine gas, and bromine.
We have found that lower TA levels will give greater pH stability with SWGs and pools with a lot of aeration (since water features have become more popular along with the use of SWGs) so we have lowered these recommended levels. I can remember on pool forum that a lot of people would complain about how often they needed to add acid. Our recommendations increase the mean time between acid additions, sometimes by quite a bit (but do not change the total amount of acid needed to move the pH.)

the range of 70-140 is way out of line. The chlorine source needs to be considered first! This also goes along with what I have observed in my customer's pools.

Also something else to consider, we have just recently seen some people with pools that were covered for the winter that opened with very low pH. Part of this is because they closed with a high TA and the CO2 was trapped under the cover instead of being able to outgas. (The higher the TA the faster CO2 will outgas.) This contributed to the pH drop and this could be disasterous for vinyl pools.


On a somewhat different note, if I remember correctly from a post by Richard, The lower TA does not reduce the overall consumption of acid but, rather, the frequency with which it needs to be added. If that is correct, I need more help understanding that.

To repeat, our recommendations increase the mean time between acid additions, sometimes by quite a bit (but do not change the total amount of acid needed to move the pH.)

To everyone else.....This is an important topic to TFP and I would hope that many of you frequent responders will chime in with your thoughts. There is no "correct" answer but rather a collective opinion that will guide the direction of the forum.

Thanks! :lol:

Hope this helps clear up why we chose the levels that we did and it was a long process that included a LOT of dialog.
We kept the final CSI in consideration along with the pool surface, which is why there are different recommendations for different pool surfaces and for the sanitizer source.

 

[Guest]

Hey, again, Jason,

(Jason and I know each others thoughts on this pretty well. I'm hoping to get input from many others on the forum :-D )

So, does keeping the TA lower result in less total acid consumption?

No, but it reduces the frequency of acid additions and this can help prevent scaling conditions from forming. The net effect of less frequent acid additions is simplified pool maintenance, is it not? Just ask anyone who has needed to add acid daily just to keep th pH below 8.0!

IF (and we all know it's a bit IF) someone is testing pH daily (and we all know that this gets old very fast!) then it's easy to keep tabs on exactly how often to add aicd. However, in the real world pH is not tested that often and often acid is not added until the pH has climbed high enough to create scaling conditions (particularly with a SWG or water features that aerate). By increasing the mean time between acid additions (which is also why we recommend borates) we minimize the possibility that scaling conditions are reached before the next pH test.

 

[chem geek]

On a somewhat different note, if I remember correctly from a post by Richard, The lower TA does not reduce the overall consumption of acid but, rather, the frequency with which it needs to be added. If that is correct, I need more help understanding that.

You are mixing up what I said about Borates vs. lower TA. Lower TA reduces not only the rate of pH rise and the frequency of acid addition, but also the cumulative amount of acid needed over time. [EDIT] This is because a lower TA results in less carbon dioxide outgassing which is a main cause for the pH to rise. [END-EDIT]

It is Borates that reduce the frequency, but not the cumulative quantity, of acid -- IF you don't change your SWG on-time. If you are able to lower your SWG on-time, perhaps because the Borates help to control algae growth, then the cumulative acid amount is lowered as well.

Richard

 

[duraleigh]

No, but it reduces the frequency of acid additions

This is the part that has me confused.

If, in a years time, you have reduced the frequency of additions, how have you not reduced the overall consumption?

 

[duraleigh]

Lower TA reduces not only the rate of pH rise and the frequency of acid addition, but also the cumulative amount of acid needed over time.

Hey, Richard, Good morning out there on the West Coat. Sorry I disremembered...(they ought to make that a real word, if you ask me)

So, now, I am more confused. (Sorry to be a bulldog on this subject) I have always understood that TA is a buffer to keep pH from fluctuating but, if I understand you, you are saying that a TA of 70 or so makes the pH more stable than if the TA were around 150.

 

[Guest]

So, now, I am more confused. (Sorry to be a bulldog on this subject) I have always understood that TA is a buffer to keep pH from fluctuating but, if I understand you, you are saying that a TA of 70 or so makes the pH more stable than if the TA were around 150.

Dave, perhaps this thead will help:
ta-what-is-it-really-t4979.html

It's a bit complex but the subject of buffers is not an easy one. The bicarbonate buffer we call TA is better at keeping pH from crashing than it is at keepting it from rising at the normal pool pH range so it's more effective with acidic sanitzer sources to stabilize the ph. When non acidic santizers are used lower TA will produde less pH rise and therefore more stable pH.

 

[Guest]

No, but it reduces the frequency of acid additions

This is the part that has me confused.

If, in a years time, you have reduced the frequency of additions, how have you not reduced the overall consumption?

If you are putting in one cup a week or 1 qt a month you are still putting in the same amount of acid, are you not. This is assuming you have a setpoint at which to add acid and a setpoint to lower your pH, i.e. you add acid when the pH reaches 7.8 and lower it to 7.6. However, as Richard pointed out, the total amount of acid also goes down with lower TA.

 

[98xc600]

When I first got the pool the TA was at 220-240. I never lowered the TA that summer and I only had to drop the PH about every month and that only requires about 3-4 cups of acid to do so. I only used about 1 to 1-1/2 gallons that summer.

After the first summer and spending the winter reading on this forum I felt I should lower my TA then I wouldn't have to worry about the PH rising. So I did but don't remember how many gallons it had taken to do that, but all of last summer my PH was still rising at about the same rate it did with a high TA level.

This spring when I filled the pool the TA was at 160. I add acid to bring it down to 90 and that required 1 gallon and 6 cups about the same amount I used the first summer without dropping the TA.

I think in my situation I use more acid trying to lower my TA than I would if i just used it to lower my PH the 3 to 4 times a summer.

 

[frustratedpoolmom]

I'm hoping to get input from many others on the forum :-D

Yah, um, nobody is going dip their toes in this Deep End conversation....

My thoughts are, when I see a TA between 100-200 and they don't have an SWG or another obvious source of aeration, I don't advice them to lower the TA. I lived with high TA for several seasons and saw no problems from it. If they post a PH that is above 7.8 AND their TA is in that higher range, and if I think they can handle the information based on how their OP reads, I MIGHT mention that IF they notice their PH drifting up or having to add Acid frequently, they can consider lowering their TA and I refer to the article on doing that. I tend to play it by ear, post by post basis... I usually prioritize what needs adjusting, TA is usually low on the list, I agree it almost always seems to be FC issues/CYA issues, and much less often is it a PH/TA issue.

As a formerly overwhelmed Noob, high TA and the possible PH drift was one of the first things I was able to grasp and it wasn't even an issue in my pool, so I don't necessarily think Noobs will be overwhelmed by it. It's not so much the individual subjects but when it is EVERYTHING all at once, it's a lot to take in, mostly what is more important? I recall wanting someone to hold my hand and step by step tell me HOW TO FIX my pool! So I do my best as Mod to try to remember on their behalf what steps they need to take and in which order.

Sometimes when there is a minor issue like TA adjusting I mention it only because I have noticed alot of noobs once they get their main problem fixed they don't come back unless there is another problem. So I think if I mention it as a future issue they may want to tackle, they'll return or maybe do further reading on it.

I don't think we're making it too complex. Maybe I should have skipped my sermon above and just said that? :lol:

 

[budster]

Waterbear, your last post above cleared up all my unasked questions. Many of my SWG clients have reported the TA/Ph climb phenomenon, and, in fact, Goldline began recommending keeping TA levels at about 70 last year. Thanks.

 

[mas985]

I gave up fighting my TA long ago. I have PH creep with my SWCG and I kept trying to keep TA down below 70 but because of high TA fill water it would quickly creep back up. However, after putting my pool on an IV acid drip, both my TA is stable within a range of 80-100 ppm and my PH stays within 7.4 - 7.7. So instead of fighting the situation, I tried to work within what I was given.

Given the varity in operating conditions between pools, to me it is more about finding out what works rather than trying to hit a specific mark.

Now if I can only figure out how to keep calcium out of the water cost effectively, I would never have to refill.

 

[chem geek]

Lower TA reduces not only the rate of pH rise and the frequency of acid addition, but also the cumulative amount of acid needed over time.

Hey, Richard, Good morning out there on the West Coat. Sorry I disremembered...(they ought to make that a real word, if you ask me)

So, now, I am more confused. (Sorry to be a bulldog on this subject) I have always understood that TA is a buffer to keep pH from fluctuating but, if I understand you, you are saying that a TA of 70 or so makes the pH more stable than if the TA were around 150.

You are forgetting that the carbonates in the water, which is mostly what makes up measured TA, are TWO things: 1) a pH buffer and 2) a source of carbon dioxide. When carbon dioxide outgasses, it raises the pH. So a higher TA may provide more pH buffering, but it also outgasses carbon dioxide faster. The latter result apparently varies as the square while the former is closer to linear. This means that at higher TA one sees a faster rate of pH rise.

As for lowering the TA when the TA is high and using acid to do so, the procedure does NOT reduce the amount of acid one needs to add over time including the amount you add to lower it initially. It simply accelerates the process, with aeration and acid addition at low pH, in order to get it over with in a short period of time. Thereafter, the rate of pH rise and the amount of acid needed is lower. In other words, it takes the same amount of acid to lower the TA by a certain amount (with the pH ending up the same) regardless of whether this is done quickly via the TA lowering procedure or more slowly over time via periodic acid addition. So, 98xc600, the total amount of acid would be the same whether you tried to lower the TA initially or did it through periodic acid addition over time -- the main reason to lower the TA would be to make the subsequent acid additions less frequent (or for adjusting the saturation index if the CH were also moderate-to-high).

Richard

 

[chem geek]

The rule for TA is very simple. If your pool experiences a rise in pH, you can try lowering the TA to see if that helps. It almost always does for non-SWG pools and usually partially helps for SWG pools. If your pool normally experiences a drop in pH (say, from using Trichlor tabs), then use a higher TA level. One does not need to force a TA if they don't have a problem. They then only need to make sure their saturation index is reasonable and can adjust other parameters such as CH as needed.

Richard

 

[Guest]

and, in fact, Goldline began recommending keeping TA levels at about 70 last year. Thanks.

WOW! Do you think the folks at Hayward are starting to notice us and what we have been doing?

 

[Guest]

Waterbear, your last post above cleared up all my unasked questions. Many of my SWG clients have reported the TA/Ph climb phenomenon, and, in fact, Goldline began recommending keeping TA levels at about 70 last year. Thanks.

This thread might be of interest to you then also!
water-balance-tips-for-a-swg-t3663.html
It explains how proper CYA levels with SWGs also helps minimize the pH climb phenomenon and how this is linked to the TA.