TFP Expert Discussion - pH and Alkalinity

TexEdmond

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Jun 16, 2021
519
Edmond, OK
Pool Size
25500
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SWG Type
Pentair Intellichlor IC-60
pH 8.1 the CSI went down a teeny bit, and then 8.2, CSI went down a teeny bit more
Maybe by then you're putting so much calcium dust into the pool that it's lowering the water's ability to precipitate more?

exactly GIF
 

nikolausp

Gold Supporter
Jul 16, 2020
136
Houston, TX
pH & CSI question....

I was tinkering around with Pool Math in trying to look at CSI shifts with my pool test numbers. pH is about 7.9 right now, and for kicks in Pool Math (android phone app), I input 8.0, 8.1, and 8.2.

I observed that as pH rises up to 7.8, 7.9, and 8.0, the CSI gets slightly higher and higher, but then when I put in pH 8.1 the CSI went down a teeny bit, and then 8.2, CSI went down a teeny bit more.

Is this... correct?

I'm still wondering about this CSI going LOWER in Pool Math when going over 8.0 pH (See my post 82).

In addition..... another question regarding pH & CSI: I've seen it said on TFP that I should try and stay at 7.8 pH or below. But I've also read that going over 7.8 isn't a big deal (up to 8.0 or so), other than scaling issues. I'm definitely concerned about scaling issues, especially in the SWG. The Borates I added hasn't really slowed down my FAST pH rise (Borates is 60ppm). Right before adding the Boric Acid, I initially got pH down to 7.5, and after 4 days it was unfortunately right back to 8.0. But at 8.0 pH, my CSI is still -.14, according to PoolMath, and my CSI is also negative at pH 8.1 (-.15 CSI), and also at pH 8.2 (-.23 CSI).

Keeping in mind scaling issues, Is it ok to be over 7.8, or even over 8.0, as long as CSI is below zero?
 

Leebo

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TFP Expert
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Jul 21, 2011
11,026
Eastern Ohio
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Is there a way you can share your test results in a new thread so we can give you some personalized advice? I suspect there’s a simple error somewhere occuring that some extra eyes can help catch. 👍
 

mknauss

Mod Squad
TFP Expert
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May 3, 2014
44,344
Laughlin, NV
Pool Size
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Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The alkalinity attributed to cyanuric acid increases with pH. As your TA testing cannot pick up this subtle difference, the CSI calculation is using a lower carbonate alkalinity and thus the CSI very slightly lowers. It is not real. Just a calculation artifact.
 
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nikolausp

Gold Supporter
Jul 16, 2020
136
Houston, TX
Is there a way you can share your test results in a new thread so we can give you some personalized advice? I suspect there’s a simple error somewhere occuring that some extra eyes can help catch. 👍

I guess I could, sure, but I'm not really that concerned about 8.1 and 8.2, since I'm not going to run my pool there. I just thought it was odd that PoolMath was lowering the CSI in those scenarios, so thought I'd mention it.

My main question now is whether it's ok to have pH of 7.9 or 8.0, as long as CSI is still below zero. I've read on TFP that scale isn't an issue as long as you keep your CSI to be negative. My pH gets to 7.8 so fast, so waiting till 8.0 would at least give me another day or two without having to add Acid. If 7.8 is the ceiling I don't want to cross, then that's fine too, it'll just be every 2 or 3 days again between Acid additions, even with 60ppm Borates, which is the same speed of pH rise as it was before adding Borates.
 
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