Rapid pH increase with SWCG

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JamesW said:
If the TA rise is from calcium carbonate from the plaster, you will get the same ppm increase in calcium hardness as you get in TA.

So, monitor the CH and TA to see if they rise by the same amount.

If they do, then that points to calcium carbonate.

How did you get an increase of 60 ppm CH in one day without adding calcium?

How did you measure a CH of 377?

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Sorry I can understand why this is confusing. My at home tests are conflated with pool store tests. I should start using Notes to indicate the differences in the log.

The 9/9 reading of 377 is from my pool store test. The previous CH test was on my Taylor test on 7/30 was 450. The 430 reading on 9/10 was also my Taylor test. The pool store always shows me with lower CH than what my test reveal at home. If you ignore the store test (377), a drop of 20 CH in about 1.5 months seems reasonable especially since I had to pump off about 8 inches of water due to Hurricane Ida.

I also have a difficult time discerning the blue endpoint of the CH test even when using the speed stir. The transition from red to blue is very gradual and really looks more purple than blue most times.

I will be testing pH, TA, and CH over the next few weeks and I'll post my results.

I can't thank you enough for your contributions to this discussion. I'll do whatever it takes to get this thing right so I'm here to learn.
 
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If it was primarily from calcium carbonate from the plaster, the calcium hardness would probably be a lot higher.

So, things just don't add up.

We're missing some critical information.
 
I assure you I'm as baffled and this is not an orchestrated riddle. I'll provide you with any information you need to help. However, I'd be willing to bet my annual salary that it's not due to the addition of any chemicals other than what you see in my logs. PoolMath is my church when it comes to maintaining this thing
 
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You are doing a thorough job, and I do not know what is going on.

I don’t know what information is missing, but it’s something unusual.

I would track the pH, TA and CH daily for two weeks to see if a graph of the TA and CH can help identify a possible reason that this is happening.

If it is from the plaster, then the calcium and TA should show similar increases.

If only the TA goes up, the only thing I can think of is baking soda.

I really don't know what else could explain the results.

High TA fill water can do it, but that seems to be ruled out.

Maybe stock up on extra reagent.

Monitor the water level to account for rain and evaporation.
 
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JamesW said:
You are doing a thorough job, and I do not know what is going on.

I don’t know what information is missing, but it’s something unusual.

I would track the pH, TA and CH daily for two weeks to see if a graph of the TA and CH can help identify a possible reason that this is happening.

If it is from the plaster, then the calcium and TA should show similar increases.

If only the TA goes up, the only thing I can think of is baking soda.

I really don't know what else could explain the results.

High TA fill water can do it, but that seems to be ruled out.

Maybe stock up on extra reagent.

Monitor the water level to account for rain and evaporation.
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No one has suggested it but don’t use any more pool store testing. That’s a good chance of why the results are all over the place.
 
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definitely stop aerating to raise ph
no more baking soda
are you holding a white card behind vial when reading ph and under same lighting conditions each time
dont put pool store tests in your log or make a note that they are pool store tests
with the ta test try wiping the tip between drops and aim for 1 drop per second
i agree with bperry, i think a lot of the conflicting info is coming from pool store testing
a ta of 50 is ok
try not to lower ph so far, i know it is counterintuitive,
but ph rises much quicker from 7.2 to 7.4 than 7.8 to 8.0
 
flippinGeo said:
And I don’t rely on it. Only take a sample in when I need acid. Mainly just to validate my own tests. I only act upon my tests.
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Then I’d recommend not logging it as it just makes your data confusing and hard to track down what’s going on, even for yourself. And the pool won’t really do a good job of validating your tests. In fact, if my tests matched the pool store, I’d wonder if I’m doing something wrong.

I think I’d stop messing with stuff for a couple weeks and just keep adding acid to keep the pH below 8. I wouldn’t try and get it lower than 7.8 or mess with the TA.
 
JamesW said:
The TA rose by 55 ppm from 65 to 120 ppm.

If that was caused by calcium carbonate, the calcium now should be 430 + 55 = 485.
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The CH seems to be tracking up with the TA, which points to calcium carbonate.

Maybe the plaster is dissolving at a high rate suddenly for some reason?

The TA has already gained 10 ppm.

Definitely odd.

It will probably take 2 weeks of daily readings to be sure.

It the plaster really is dissolving at this rate, the TA and calcium will be very difficult to control.

Keeping the CSI as close to 0.0 as possible will reduce plaster loss, but it seems like it will be a very difficult situation to manage.
 

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Today’s log is in. pH went up .2 but TA and CH held. I’ll keep on it and loop back in a week or so. Just ordered more reagent and buffer. I tried the high CH method first but realized it was too course of a measurement so went back to the 25ml test.

you can see my CH didn’t rise any until this past week at the same time my TA went out of whack while I was away. Something bad happened while I was away for sure. Perhaps all this Dang acid I’m adding is tearing up my plaster
 
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Maybe scale dissolving, but it would require about 12.84 lbs. of calcium carbonate scale to dissolve and I don't know of any reason that that much scale would dissolve suddenly unless someone aggressively brushed with a stainless steel brush or added a lot of acid and allowed the acid to sit on the bottom of the pool.
 
Day 2 pH +.2, TA +10, CH =

attached a photo of the pitting in the plaster. It’s windy here today so not the best photo. I did brush quite a bit during the borax dosing. And I dose my acid by ramping up the pump to 3000 rpm and pouring a pencil thin right in front of the returns. Because I have to use such large doses I typically split it between the deep end and shallow end returns.
 

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Definitely a strange situation.

The only thing that seems like it could contribute to the steady TA rise is plaster or scale dissolving, but those really don't dissolve that fast unless something else is happening.

Thanks for the updates.

Hopefully, some sort of answer will come from watching the numbers over time.
 
looking at your pool logs
i would think your ta is 70 and the other results are test accuracy or outright errors
your 480/490ch is within test accuracy
the rainfall would have aerated the pool causing ph rise
again try to only lower ph to 7.8
when your ta gets down to around 50 i am sure your ph rise will slow down considerably
 
Day 4 - pH -.2 (7.8*), TA -10 (70), CH no change (480)
* I dosed yesterday to target 7.6. I didn’t test to confirm after dosage but I assume it reached 7.6 then rose .2 to 7.8. Still -.2 from yesterday’s test. But I’m assuming -.4 then +.2
 

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