New Pool, dialing in, high TA, takes a lot of acid to lower pH

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J

JasonBigCountry

Member
Jun 21, 2022
23
Abilene, Texas
Pool Size
20000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hi,
A lot in that subject, but it's really one question to start with.

Again, new pool (about a month old), filled with well water (well, that ship has sailed - knowing what I know now, I don't know that I'd do that again...)

Went from using test strips (Frog brand, came with my Pool Tender) to TF Pro - I'm still new to using it, so take my readings with that in mind... I may be doing it wrong :) (I have read the instructions that came with it, plus the extended instructions I found here - they're much better, and should come with it!)

Current numbers (some a couple days old, some a couple hours old):
FC : 3ppm
pH: 7.2 (I think, and there's a reason it's low right now - I'm working to lower TA)
TA: 200ppm (down from probably over 275)
CH: 650...? I'm not confident in this number
CYA: 55 (I've deliberately got it a bit high, as I was flying through chlorine)

I was having a problem with my pH going up "continuously", and also noted that adding ph-down wasn't nearly as effective as the instructions indicated it should be.

I've since read all I can find here about TA and pH, and now understand that with my TA so high as it was (and still is), it would tend to ratchet my pH up fairly quickly. So, I'm on a mission to lower TA. I've build a PVC aeration aid device (as shown in a few posts elsewhere), and I've been doing the add acid (switched from using Dry Acid / ph-down to usinng Muriatic - 31.45% now) to get pH down, then aerate.

It's making progress.
I've added 4 gallons so far (over about 12 hours) and the pH hasn't gone down nearly as much as I expected (hence, I'd keep adding more - leaving at least 20-30 mins between a pour and a pH read, with the pump running).

My question: Is it normal for it to have a reduced impact (relative to what the calculators indicate you could expect) due to the high TA? Or is it normal that the calculations (even from Pool Math) are wildly wrong compared to reality?

I feel like I'm making progress, just curious why I was able to add four gallons in such a short time frame to get the pH down. Actually, I think to get from 8.4 to about 6.8-7.2 (hard to read), took be about 3 gallons over about four hours. Added another gallon this morning, as it was back up to about 7.2 (with more confidence).

(I probably just need a better way to read pH - I suck at this color comparo game!)

Thanks :)
 
Hey, welcome to TFP!

JasonBigCountry said:
Is it normal for it to have a reduced impact (relative to what the calculators indicate you could expect) due to the high TA? Or is it normal that the calculations (even from Pool Math) are wildly wrong compared to reality?
Click to expand...
It is possible. Smaller changes (.4) with pH between 7.2-7.8 at TA around 80-120 (no borates) will generally be accurate when you use "effects of adding."

When you are done with the process and your pH is back to normal and TA is 60-80, results should match expectation. If you still have the same problem after your chems stabilize, it may be that your pool is a bit bigger than you think. Best advice I can give you is to increase the size of your pool in pool math in increments of 500 gallons, until the EXPECTED change matches the ACTUAL change.
 
Ok, thanks for that info - I'll see what I find.
A few hours ago, pH was back up to 7.5, TA indicated 225 using the 10ml variant of the TA test. I let the pool idle for a few hours, in case anyone wanted to swim while it was at a 'normal' range.

Now that the kiddos are settling in, I've just added another gallon (the fifth in about 24 hours), and am about to go back and re-check pH, and, hopefully, go back to aerating.
 
JasonBigCountry said:
Ok, thanks for that info - I'll see what I find.
A few hours ago, pH was back up to 7.5, TA indicated 225 using the 10ml variant of the TA test. I let the pool idle for a few hours, in case anyone wanted to swim while it was at a 'normal' range.

Now that the kiddos are settling in, I've just added another gallon (the fifth in about 24 hours), and am about to go back and re-check pH, and, hopefully, go back to aerating.
Click to expand...

How confident are you in the Ph test accuracy? Are you using the comparator block or did you purchase the electronic ph meter? 5 gallons of full strength acid in 24 hours seems like a lot. A whole lot. According to pool math, 5 gallons would decrease your TA by 125ppm. Your ph would be extremely low unless you have some very impressive aeration.
 
Hi,
@Sunnydaze, I'm not confident in the pH accuracy at all. I very rarely use the test block and end up with a good color match. Usually it's like, "Hm.. It's orangish-reddish.... I think it's kinda like the 7.2, but... it may be lower or higher. Definitely not the 6.8. Is it 7.5? Not sure."
I sometimes try my test strips as well (I have some from Frog, and some AquaChek 7), and results with those are sketchy, too.

This morning I confidently decided that I had a pH of 7.35 (i.e., between the 7.2 and the 7.5 on the test block), but then decided to double check with AquaChek 7. Twice. First time I thought it looked like 7.5, second time, 7.2, maybe 6.8.

Just shoot me :)

I decided NOT to add another batch of acid, and just let it continue aerating. I guess if I wait until I'm sure the pH is back on the higher side again (I can usually discern the difference between the high end and the low end with no doubt), at least that will help.

My TA (this morning) was 180 or 190 (I recorded it as 190, but the color shift between 18 drops and 19 drops was very subtle, if present. I was sure that adding the 20th made no difference). My final reading last night was 170 - I'm assuming the TA didn't actually drift up, and that's it more a matter of my testing accuracy (I didn't bother using the damp cloth to wipe the tip each time in either test), or due to temperature changes in the water or air.

So, yeah, since I've started, I'd say I've dropped the TA by AT LEAST 60, and maybe a bit over 100, but my confidence in my initial readings is not as high as it is in my more recent readings.

Any recommendations for a more reliable way of reading pH would be welcome. I've looked at many pH meters on Amazon, but they all seem to require having distilled water handy, semi-regular calibration, and require that you keep the tip damp continuously (or have to recalibrate). Prices seem to vary from $15 to $100, but same story with water and calibration. Seems like it might be more fiddly than it's worth. I've also looked for better pH litmus strips (hoping for something that provides 0.1 resolution), but haven't found any, yet.
 
Members report good results with an Apera 60 pH meter.

Have you varied the number of pH reagent drops used? Try 4 or 6 and see if it helps.
 
JasonBigCountry said:
Ok, thanks for that info - I'll see what I find.
A few hours ago, pH was back up to 7.5, TA indicated 225 using the 10ml variant of the TA test. I let the pool idle for a few hours, in case anyone wanted to swim while it was at a 'normal' range.

Now that the kiddos are settling in, I've just added another gallon (the fifth in about 24 hours), and am about to go back and re-check pH, and, hopefully, go back to aerating.
Click to expand...
TA is measured with a 25ml test - can you describe the method using only 10ml?

I also have high TA well water; in times where I need to add a lot of water, I dump MA with target for 7.0 and it typically changes quickly.
 
JasonBigCountry said:
And thanks for the tip/lead on the Apera 60 - I'll check it out.
Click to expand...
I just picked up the Apera PH60 yesterday. The instructions are poorly written but the device is easy to use once you decipher them. I bought it because I didn't like staring at the color block with different lighting and backgrounds to figure out what my pH was. I'm OCD and want accuracy even if it doesn't matter. My understanding is a properly calibrated Apera PH60 is very accurate. Having said that, it isn't any quicker to use than drops and an accuracy of .2 with the drops is close enough for our pools. I just love gadgets :)

I think a good use case for the Apera PH60 is somebody who is color blind or really struggles with the color block.
 
reggiehammond said:
TA is measured with a 25ml test - can you describe the method using only 10ml?
Click to expand...
With the Taylor test kit and a 10mL water sample you add 1 drop of R-0007, 3 drops of R-0008 then add R-0009 dropwise until color changes from green to red and multiply the drops by 25.
 
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bertschb said:
I just picked up the Apera PH60 yesterday. The instructions are poorly written but the device is easy to use once you decipher them. I bought it because I didn't like staring at the color block with different lighting and backgrounds to figure out what my pH was. I'm OCD and want accuracy even if it doesn't matter. My understanding is a properly calibrated Apera PH60 is very accurate. Having said that, it isn't any quicker to use than drops and an accuracy of .2 with the drops is close enough for our pools. I just love gadgets :)

I think a good use case for the Apera PH60 is somebody who is color blind or really struggles with the color block.
Click to expand...
Ha! Yep, your self assessment sounds a lot like mine is likely to sound. I have a hunch that once I get some confidence in reading the colors, compared to something with a digital readout, I may just used the color block again. But, until I have that confidence and judgement... I just don't know if I'm reading it right. I'll order the PH60 shortly. I like that it appears to come with enough buffer to do multiple cals. I assume I'll still have to get a jug of distilled water to keep on hand. Not sure.
 
reggiehammond said:
TA is measured with a 25ml test - can you describe the method using only 10ml?

I also have high TA well water; in times where I need to add a lot of water, I dump MA with target for 7.0 and it typically changes quickly.
Click to expand...
bertschb said:
With the Taylor test kit and a 10mL water sample you add 1 drop of R-0007, 3 drops of R-0008 then add R-0009 dropwise until color changes from green to red and multiply the drops by 25.
Click to expand...
@reggie, @brian,
Yep, what Brian said, and here's where I found that info: Extended Test Kit Directions Archives
These are the "extended directions" you wish came with your TF-100 / TF-Pro kit. Heck, there's a QR code that came with mine that might take me there, but I haven't tried it out. :) I found them by searching for info about TA and pH, or how to use the tests, or something. I printed them out, folded them, and put them in my kit. I found them very helpful, as I also learned I was doing some of the tests not-quite-right (hence my uncertainty about just how high my TA was at the beginning of the process. I was adding drops until it was "red enough that I thought it counted", instead of "as red as it was going to get."
 
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JasonBigCountry said:
I assume I'll still have to get a jug of distilled water to keep on hand. Not sure.
Click to expand...
Yep. I picked up two gallons of distilled water while we were at the grocery store yesterday. The directions say to use "pure water" for rinsing. What the heck is that???? I interpreted that to mean distilled water. I ordered extra buffer and soaking solution. I also ordered some small plastic "Dixie cups" to use for my rinsing and pool water samples. As I said, using the PH60 won't be faster than the drops but it will be more fun and as we all know, digital readouts are more accurate :)
 
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