Added Boric Acid

red-beard

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I added the Boric acid and see the other thread about using the Crud from Home Depot.

My TA did not change based on the TA test, still about 70. I'm also increasing my CYA to 80, about 1/2 way there (76 with my eyes). The goal for me is to reduce my CA down to a level that the maximum pH is 7.9-8.0.
If my reading really is 70, then, the Carbonate Alkalinity should be TA - (CYA/3) and (Borates/8). This means a CA of about 38. Using this chart, being between 30 and 40 Carbonate Alkalinity, I should have a ceiling of just under 8.0. Which should be a very respectful pool pH these days. Even with an 8.0 pH, the CSI is a negative -0.12 (85F, 50 ppm Borates, 80 CYA, TA 70, Salt 3000, CH 350).
Should I bother trying to drop the TA to 60? It looks like leaving it 70 is better.

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red-beard

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Fill Water in ppm: FC 0.6, CC 2.6, pH 8.0, TA 80, CH 90

Our water system uses Chloramines for sanitation. And so far this year, I have had far more rain than anything else.
 

JoyfulNoise

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Your fill water TA is 80ppm and remember, for municipal fill water, that is pure CARBONATE alkalinity. That is what’s going to drive your TA level in the pool more than anything else. I would say that 70ppm TA is reasonable but anything lower is going to mean constant acid additions. Even to maintain 70ppm I think you’ll be adding acid at least once every 2 weeks. There’s no harm in trying to go lower if you want, I think it’s just a matter of how often you want to add acid.
 

red-beard

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It will depend on the summer, how much water I have to add. We've had about 10 inches of rain in the past 2 weeks. But now no rain in the forecast for a week...And the heat is on! Probably cool by your standards, but 96 with a dewpoint around 74-75 is hot and humid here. Summer is here.

I just looked, we are both 87F right now! But your dewpoint is 23F and mine is 74F
 

red-beard

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So I'm going to leave it alone and not bother to drop the TA. And it looks like I should target a much higher pH now for the CSI. 7.7 and below I'm under -0.3 CSI
 

JamesW

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Mar 2, 2011
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Carbonate Alkalinity should be TA - (CYA/3) and (Borates/8).
The correction factor for each depends on the pH.

Adjusted TA = TA – (CYA X CYA C.F) – (Borate x Borate CF)

Borate C.F (correction factor) based on pH.

pH.......CF

7.2.....0.051

7.4.......0.0786

7.6......0.1248

7.8......0.1989

Cyanuric Acid correction factor based on pH.

pH........CF

7.0.......0.22

7.1.......0.24

7.2.......0.26

7.3.......0.28

7.4.......0.30

7.5.......0.32

7.6.......0.33

7.7.......0.34

7.8.......0.35

7.9.......0.36

For example, if the pH = 7.6, TA = 90, Borate = 50 and CYA = 70, the adjusted alkalinity is 90 - (70 x 0.33) – (50 x 0.1248) = 60.66.

The Taylor book gives slightly different values than I got, but not too far off.

Maybe they used a different pKa for boric acid.

1623170016190.png
 
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red-beard

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Matt, thanks for the help on this. I have the pool pretty well dialed in. Just trying to make it as trouble free as possible.
 

red-beard

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James - Thanks for pointing out the pH correction factors.

I'm heading for a pH of 7.9-7.8, so the new CA = 70 - (75 *(.36 or .35)) - (50 *.1989) = 33-34. Again, this puts me inside the 7.9-8.0 pH ceiling. Dropping from 7.9 to 7.8 is only about 1/5 of a gallon MA in my pool. I check ~weekly, so we'll see where it goes now. At the moment (after adding the Boric Acid and a little CYA) my pH is hovering around 7.6, so the factors I used were correct. And 1/8 is close enough to 0.1248...

OTOH, if my CA is 38 right now, I should test closer to 80 when the pH is higher? I think I'm inside the test accuracy/capability. I'll see.
 

JoyfulNoise

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June is the hottest and driest month in Tucson. Our RH can dip all the way down to 10% here. It stays that way until about mid July when the “monsoon season” hit (it’s not really “monsoons” … more like a microburst downpour that last about 10mins … people here are so silly). Then we’ll get sporadic microbursts of rain for a few weeks. Then late August it gets hot and dry until the weather cools in Oct. we have about 4 miserable months here in Tucson then the rest of the year is cool and pleasant. Winters are fabulous here. Most days I’m wearing shorts and hoody … it’s a cold day when I have to put blue jeans on.

I say let it ride for now and see what the pool care regimen is like. If you go 10 to 14 days between acid additions, that’s pretty much as low maintenance as it gets. We southern and western folks will never have stable pH like the northern vinyl pools do, the water and plaster works against us constantly. So it’s just a matter of minimizing the chemical care routine. I think you’ll find the borates to be a helpful tool. I use 60-80ppm borates but that’s just me. 50ppm is gone for most folks.
 

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JoyfulNoise

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I’ve sworn off humidity forever … grew up in NY and lived there until my early 30’s … more than enough snow, rain and humid summer days. “Dry heat” is fine by me ….
 

red-beard

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I’ve sworn off humidity forever … grew up in NY and lived there until my early 30’s … more than enough snow, rain and humid summer days. “Dry heat” is fine by me ….
I did the same, in Upstate (Schenectady - yes, GE). I am done with winter! Grew up down here, then 25 years up there (or other parts of the world). I can deal with the heat and humidity. But I could do without the hurricanes. We're moving inland in the next 5 years or so. North of Austin or Dallas (or both...).
 

red-beard

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Everything has stabilized, and the TA reading is now "80ppm". if I'm reading the test correctly. If the test stops when the color changes, then 70. If the test stops when the sample turns RED, then it is 80. I'm guessing here, but I expect my TA is between 70 and 80 in reality.
 

JoyfulNoise

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It’s probably 90ppm.
The TA test is read as done when the red color stops changing, then subtract 1 drop.
 

red-beard

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On the TA test, I add the sulphuric acid drop by drop. At 7 drops, the solution changes color to not green and not red. At 8 drops it turns definite red. I tried a 9th drop, no change in the red color. According my my Taylor directions, that would be TA = 80 ppm. @JoyfulNoise Matt What is you take?

On stability. pH seems to be quite stable. My pH meter has a reading of 7.9. Has not changed in a week.

With CYA 80, Borates 50, Temp 90F, CH of 275, Salt 3000, pH 7.9, Pool math says CSI of -0.08. That seems like a good value. At 8.0, the CSI is still -0.03. not until 8.1 does the CSI go positive. I could drop the pH to 7.7 or 7.8, but it doesn't change CSI that much.

Pool water seems very nice (if warm a bit warm...). And I'm not planning to add MA until/unless the pH goes to 8.0. Any thoughts? I'm trying for minimal work. It is taking a lot of work to get to minimal work.
 

JoyfulNoise

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That is the correct way to read it , TA is 80ppm. Sounds like you’ve contracted a case of sparklipoolitis … sadly, there is no cure and it will be a life-long affliction. Sparklipoolitis is characterized by an obsessive, near borderline psychosis, surrounding the physical and aesthetic qualities of large bodies of water, an addiction to constant water quality testing, and a debilitating need to constantly perfect ones own pool water. You may also experience the inability to swim in any other body of recreational water and some of those afflicted lose contact with friends and relatives over pool care habits. It’s a sad, sad disease that the medical community is perplexed by and hopes to find a cure for. For now, just regularly consume your favorite adult beverage and try to swim as much as you can without constantly harassing people about not relieving themselves in your pool.
 

red-beard

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Sounds like you’ve contracted a case of sparklipoolitis … sadly, there is no cure and it will be a life-long affliction. Sparklipoolitis is characterized by an obsessive, near borderline psychosis, surrounding the physical and aesthetic qualities of large bodies of water, an addiction to constant water quality testing, and a debilitating need to constantly perfect ones own pool water.
Yep, I'm, afflicted
You may also experience the inability to swim in any other body of recreational water
Definitely true! Yuck!
You...constantly harassing people about not relieving themselves in your pool.
Snort! Just last night...
 
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