Unexplained pH rise

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While 0.60 to -0.60 is okay for CSI, keeping it within 0.30 to -0.30 is preferred.
And with a SWG, 0.00 to -0.30 is better to help prevent calcuim buildup in the SWG.

Is your pool presently fully closed or are you adding chemicals now?
If adding chemicals, post a full set of current test results.
Your SWG won't produce chlorine until the water temp is around 55 degrees.
 
proavia said:
While 0.60 to -0.60 is okay for CSI, keeping it within 0.30 to -0.30 is preferred.
And with a SWG, 0.00 to -0.30 is better to help prevent calcuim buildup in the SWG.

Is your pool presently fully closed or are you adding chemicals now?
If adding chemicals, post a full set of current test results.
Your SWG won't produce chlorine until the water temp is around 55 degrees.
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My pool is fully winterized in NJ but I open the cover at 2 corners every 6 or 7 days and drop in 2 circulation pumps to mix the 1.25 cups acid. The swg was removed during winterization and i used liquid chlorine when needed. I only check pH and chlorine weekly and other chemicals if I drain a lot of water due to rain. I only had to add chlorine once since the water got very cold. My last readings: ph = 8.6 before acid addition and 7.8 after. Cya = 30, alkalinity = 60, calcium = 525 ppm , salt = 2200ppm, chlorine = 6ppm, water temp 38F. The reason for all this is because I was told that during 1st year of plaster curing it’s very important to keep chemicals balanced and to follow LSI.
 
My fill water has a TA of 30 ppm and a CH of 80 ppm.
No, the CH of the pool doesn't increase over time.
I do add TA increaser/Baking soda on occasion. I add it when it dips down below 50, I try to keep my pool TA at about 50.

The SWG would be about 15m from the return jet.

My LSI is normally around -0.4

I do refill maybe every two weeks, when the level drops by about 3cm
 
JamesW said:
How much have you added?
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I just added 500 gm before, my TA was at 45ppm.
It’s difficult for me to give you an accurate quantity over a long time period. It might be 1 kg every six weeks.
I know I should be more diligent in recording amounts

Do you think the distance the SWG is from the return could be a factor?
 
xDom said:
I keep my TA at around 50 ppm and I keep my pH at about 7.7 to 8. I use 5 litres ( 1.3 gallons ) every two months in a 30 000 litre ( 7925 gallon ) pool. Do think this is normal usage?
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What is the concentration of acid?
xDom said:
The SWG would be about 15m from the return jet.
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I suspect that the distance is enough to dissolve all of the chlorine gas.
xDom said:
Do you think the distance the SWG is from the return could be a factor?
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Seems unlikely, but I don't know that it can be ruled out.

The baking soda explains some of the TA rise.

5 liters of 31.45% acid will lower the TA by 83 ppm in a 30,000 liter pool.

1.444 kg baking soda will raise the TA by 29 ppm.
xDom said:
I just added 500 gm before, my TA was at 45ppm.
It’s difficult for me to give you an accurate quantity over a long time period. It might be 1 kg every six weeks.
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There is about 54 ppm of TA rise that is not accounted for.
 
xDom said:
I just added 500 gm before, my TA was at 45ppm.
It’s difficult for me to give you an accurate quantity over a long time period. It might be 1 kg every six weeks.
I know I should be more diligent in recording amounts

Do you think the distance the SWG is from the return could be a factor?
Click to expand...

You should be able to find an adding pattern where you don't need any TA increaser anymore. There's not much point in aiming for TA 50 in an attempt to reduce po pH rise, when you them have to add bicarb again.

Try to add acid a bit later, let pH come up a bit higher.
 
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key1cc said:
😢
five years later?!?
My pool is 9 months old and I was told 10 months to 1 year to fully cure and stop needing to make such frequent acid additions... You just told me there is no santa claus.....
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Every pool is different, so don't stop belivin'! Unless you were just looking for an excuse to eat the cookies yourself!

Bad Santa | TheMarckoguy


I haven't made a detailed study of it. I've just assumed that my fill water is driving the pH (since I have no spa or water features). When I first came on board here I was obsessed with controlling my TA. I used all the tricks. Then, at the advice of our experts, I stopped doing that and just treated the pH as needed. The TA stabilized on its own, and my acid demand is what it is. I actually put in my acid dispenser before I knew if my pH was going to stabilize or not. Turned out to be a good decision, because I still use the heck out of the thing.

But you might wait a year or two to see if you have a pressing need for an acid system. You won't really know before then.
 
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mgtfp said:
You should be able to find an adding pattern where you don't need any TA increaser anymore. There's not much point in aiming for TA 50 in an attempt to reduce po pH rise, when you them have to add bicarb again.

Try to add acid a bit later, let pH come up a bit higher.
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So you wouldn’t see a problem if my pool sat at say, 8.0?
I didn’t think it would be possible to reach a point where I no longer need to add anything to keep TA stable? Given my fill water TA is 30 ppm wouldn’t it gradually decrease?

To be honest, and I say this respectfully, the TA minimum of 50 and ph starting with a 7 are values that I have maintained because they are suggested and repeated here on TFP.

I remember a post James made a while ago on the Deep End ( I can find it if needed) where he said that he believes TA isn’t as important in SWG pools as some of the other parameters as the only reason pH can crash is if someone pours too much acid in. I’m the only one adding MA to my pool so I can control that aspect.

I thought this was a great comment! Maybe I’ve taken it out of context though?

So given my fill water has a TA of 30 ppm, this is the value where it probably wouldn’t go below if I never added increaser?
If I let the pH settle at say 8.0 it would be likely that the amount of acid needed would be negligible and I would have basically stopped needed to add TA increaser.

Edit: I checked on the table in the pH/TA wiki and at a TA of 40 and a pH of 8 the CO2 levels are in equilibrium.

Basically what I’m saying is that I hear that every pool is different, is it possible that the point where my pool is balanced is slightly outside of TfP recommendations?
 
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Dirk said:
Every pool is different, so don't stop belivin'! Unless you were just looking for an excuse to eat the cookies yourself!

Bad Santa | TheMarckoguy


I haven't made a detailed study of it. I've just assumed that my fill water is driving the pH (since I have no spa or water features). When I first came on board here I was obsessed with controlling my TA. I used all the tricks. Then, at the advice of our experts, I stopped doing that and just treated the pH as needed. The TA stabilized on its own, and my acid demand is what it is. I actually put in my acid dispenser before I knew if my pH was going to stabilize or not. Turned out to be a good decision, because I still use the heck out of the thing.

But you might wait a year or two to see if you have a pressing need for an acid system. You won't really know before then.
Click to expand...
Do you know what your TA has stabilised at?
 

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xDom said:
Do you know what your TA has stabilised at?
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Last I tested my TA was 70. I've seen it bounce around some, maybe as low as 50 or as high as 80 (this range is after it settled down), but 70 seems to be it's happy place.

I'm able to maintain all my levels almost dead center in TFP ranges (FC*, pH, TA, CH, CYA). And because I have automated chlorine and acid, I don't subject my pool to swings. Every day the levels are dead center. Really every hour of every day. I can't prove it, but I think reducing or eliminating the roller coaster affect for all levels just makes things easier, and more stable.

* I run FC a little hot.

To expand my anti-roller coaster MO, this year I'm starting a new regime. Since I cannot stop CH-rise entirely (I can only slow it way down with a water softener), I am no longer going to let CH get almost out of range before correcting it with a partial water exchange (it took about five years to get too high last time). I'm going to do much smaller exchanges every spring, and "re-center" CH once a year, instead of every five.

Not only will this keep my pH and CSI stable year-over-year, I won't have to exchange too much water at a time. I am of the school of thought that removing water from any pool is just gambling with the pool's finish and/or structure (any type of pool), so the less I exchange, the better. I figure I'll only need to exchange 3-6" each year.
 
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Here's a tip that might help. Athough not exactly TFP doctrine, in reality, anyone using automation is pretty much doing this same thing.

You don't necessarily have to test pH every time you dose. You can treat your manual dosing as I do my automated dosing. I set my machine to dose the same amount each day, and only test once a week. If the pH is off, I correct it that same day, then forget about it until a week later. Depending on how far off it was, I will adjust the setting on my machine. Sort of a "best guess."

You could average your dosing and determine your daily amount (or bi-daily, or more, whatever). You take a minute to dose that amount, but without testing. Quick and easy, go about your day. Then once a week (or whatever interval you're comfortable with), test pH. Make the overall adjustment then, and alter the daily dose amount if necessary for the following week. A week later you'll know if your new daily amount is right. It's just like tweaking the adjustment on an acid dispenser, or an SWG. We tweak those settings only so often, and test only so often to make sure the tweaking is working. See?

That might take some of the chore out of the chore. Eventually you'll know: 1/2 cup a day (or whatever amount), then test weekly to confirm. Adjust as needed. That's much better, and more stable, than waiting several days, testing, blasting your pH with acid and repeating that schedule.
 
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Before I automated, I built a gizmo to dose acid and chlorine that allowed me to walk away while it gently and slowly dispensed. I could go do other pool or yard chores, and didn't have to stand over an acid jug pouring slowing while breathing fumes. This made manual dispensing far less of a chore. You wouldn't need to be as elaborate. ("Elaborate" is my middle name.) A 3' 2x6 and a measuring cup would work just as well.

This is in the middle of a very long thread, in my younger days, where I explored all sorts of aspects of pH and pouring acid.

Getting ready for SWG

You don't want to have a container that does not vent if you are going to store the acid in it. Acid containers have caps that vent the fumes. You can estimate how much has poured out of the bottle with that type of hose. It's not like you have to have an exact amount each time, it's only...
www.troublefreepool.com www.troublefreepool.com

I actually still use this quite a bit, especially in the winter when I have to use liquid chlorine instead of my SWG.
 
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xDom said:
So given my fill water has a TA of 30 ppm, this is the value where it probably wouldn’t go below if I never added increaser?
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It would still increase from there. Evaporation leaves TA behind, and then you add more with fresh fill water. But with TA 30 fill water, that should be a slow process.

And each acid addition will bring TA down. There's a simple rule of thumb for those thinking metric: Take your pool volume in hecto litre, replace the hecto with a milli, and that's the acid amount that will reduce your pool by pretty much 5ppm. Example: You have a 30000 litre pool, that's 300 hecto litres. An acid addition of 300 milli litres (full strength MA) will reduce your TA by about 5ppm.

I wouldn't go below 50. You want some buffering left for things going wrong. Acid container slipped, acid added instead of bleach, it has all happened before. Pool service who takes over while on holidays throws in a few pucks. Whatever.

One issue with pH 8 is that you don't know if pH is actually higher, unless you have a well calibrated electronic meter.

Australian standard AS 3634 for private pools wants pH to be not higher than 7.8. This doesn't make much sense as a standalone rule, for the risks with higher pH they are mentioning things like reduced chlorine effectiveness (which is only valid without CYA) or scaling (it's not pH alone, CSI counts). In the end it's up to you what to make of that, and that you understand what you are doing and potential consequences.

Another thing is that around pH 8, and quite pronounced above 8, FC loss to UV starts to become more significant, particularly at higher FC/CYA ratios:

Chlorine and pH relationships. Chem experts knowledge?

OK, so I am a newbie. But, I’m ignorant of pH within Chlorine relationships. I can find very much data here on Chlorine/CYA, but what about pH? Basically without getting too technical……haha, (I’ve read Chem Geeks articles) I am trying to figure out the effectiveness of Chlorine at different pH...
www.troublefreepool.com www.troublefreepool.com

I usually let pH ride through winter up to 8. In summer, I usually keep it below 7.8, I need those acid additions then anyway to stop my TA from rising. TA usually between 70 and 90.
 
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This thread has gone a bit off the well-traveled road and into the weeds.

Dirk, I think your method is TFPC, at least based on not adding chemicals without a valid reason and based on reliable test results. You have the history of trends and know what can be expected, and it's backed by reliable test results. It would be unwise, and not part of TFPC, to adopt that method from the outset.

xDom, please post full test results, as follows, to help people answer questions reliably.

FC x.x
CC x.x
pH x.x
TA xx(x)
CH xxx
CYA xx

xDom, which test kit are you using and how old is it? When you test TA, do you keep adding drops until there is no further colour change, and include the last drop in your result?
 
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needsajet said:
Dirk, I think your method is TFPC, at least based on not adding chemicals without a valid reason and based on reliable test results. You have the history of trends and know what can be expected, and it's backed by reliable test results. It would be unwise, and not part of TFPC, to adopt that method from the outset.
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Cool. I try to stray as little from the teaching doctrine as possible, to avoid confusing those new to our MO. But throw in my "flavor" of it in small batches. The reality is, no method will be reliable if the user doesn't or can't get it done. I made a science (for myself) out of finding ways to adhere to TFPC with the absolute minimum effort necessary (hence all my automation). That's what works for me, and my pool. We each find our own way, ideally maintaining TFP's over-arching guidance and science.
 
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mgtfp said:
Another thing is that around pH 8, and quite pronounced above 8, FC loss to UV starts to become more significant, particularly at higher FC/CYA ratios:
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I did actually read up about this after I was questioning the whole “pH in the 7’s “ idea in a thread a few months ago.
 
needsajet said:
This thread has gone a bit off the well-traveled road and into the weeds.

Dirk, I think your method is TFPC, at least based on not adding chemicals without a valid reason and based on reliable test results. You have the history of trends and know what can be expected, and it's backed by reliable test results. It would be unwise, and not part of TFPC, to adopt that method from the outset.

xDom, please post full test results, as follows, to help people answer questions reliably.

FC x.x
CC x.x
pH x.x
TA xx(x)
CH xxx
CYA xx

xDom, which test kit are you using and how old is it? When you test TA, do you keep adding drops until there is no further colour change, and include the last drop in your result?
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Sorry mate!

FC 6.5
CC 0
pH. 8
TA. 50
CH. 300
CYA. 65




I use a clear choice testing kit with reagents all within their use period.
 
xDom said:
Sorry mate!

FC 6.5
CC 0
pH. 8
TA. 50
CH. 300
CYA. 65




I use a clear choice testing kit with reagents all within their use period.
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That’s a near perfect CSI of -0.02. You’re fine.

Though you need salt and temp to get a more accurate CSI.
 
Dirk said:
That’s a near perfect CSI of -0.02. You’re fine.

Though you need salt and temp to get a more accurate CSI.
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I’ve been using an LSI calculator, do you have a link for a CSI?
LSI tells me I’m aggressive?
 

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