LSI / CSI during the winter

eqbob

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Jul 26, 2012
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Central Texas
#1
An input to the LSI and CSI is temperature. Because of that, the same chemistry values used during the summer which produce a balanced index, lead to a corrosive index as the water temperature plummets (Thanks Bering sea storms <G>)

For CSI
Increasing CYA is not good, because that takes CSI more negative
Increasing TA will make it less negative, but obviously that's going to affect your pH swings
You could increase your CH, but that has a fairly minimal impact on the overall value.
You could let your goal pH stay higher, from say 7.6 to 7.8

There's a similar set of statements that cab be made about LSI

So what do others do to compensate for the colder temperatures and still keep everything balanced?!?

Now know that last winter, the pool was so abused by the pool service people who showed up once every 2-4 weeks, dumped in a gallon of muriatic, and left and came back 2-4 weeks later.
 

JamesW

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Mar 3, 2011
12,647
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#2
Allowing the pH to go higher will give you the most control because you can lower it easily later. A higher pH will allow you to also maintain a higher TA without excessive pH drift.

Adding calcium can help, but as you point out, the impact is fairly small, and it's not easy to remove calcium, especially if your fill water is high in calcium.
 

zethacat

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Sep 23, 2013
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Dallas-Ft. Worth Metroplex, TX
#3
I have a TA of 70, CH 250 and CYA 50. Water temp is easily in the 40s. I wait for PH to get up around 8 and then add about 12 oz of MA which brings me down to maybe 7.5. 7.5 gives me a CSI of -0.6 but it doesn't stay there long. Each day PH goes up by .1 so I am only adding acid every 3 or 4 days. I'm thinking of letting it get to 8.2 because that is a 0 CSI for me and my PH rise is pretty predictable. I don't see any evidence of corrosion -- plaster is only 2 months old -- it could actually use some more quartz exposed if anything and has a couple of brown spots I wish would dissolve. I brush at least twice a week. I think I'm safe continuing on this path. Well, at least I hope I am. :D I was thinking about bringing up the TA to compensate but I'm afraid that will make my PH rise faster, and I don't want to be handling acid more than once a week if I can avoid it.

In response to OP; A gallon of MA would probably bring my PH down to acid bath levels .. I can't imagine what it would do to your pool which has 2000 gallons less!!!!
 

JasonLion

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May 7, 2007
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#4
In the winter, as the temperature goes down, the PH naturally goes up, resulting in the CSI staying at about the same level it starts with. If you are tracking and adjusting PH, you should allow this natural PH increase instead of "correcting" it.
 

eqbob

Well-known member
Jul 26, 2012
436
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Central Texas
#5
In the winter, as the temperature goes down, the PH naturally goes up, resulting in the CSI staying at about the same level it starts with. If you are tracking and adjusting PH, you should allow this natural PH increase instead of "correcting" it.
Ok. Good info all and thanks. At what pH target then should I aim for starting a corrective action? Especially since the test kits only show 8.0?
 

zethacat

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Sep 23, 2013
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Dallas-Ft. Worth Metroplex, TX
#6
Mine goes up to 8.2. Chem geek has told me that if you don't have metals in the water, there is no issue maintaining a high PH. Since its really only necessary during very cold weather, once it starts warming up your CSI will want a lower PH more suitable for swimming without having to adjust your other numbers.
 

eqbob

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Jul 26, 2012
436
0
Central Texas
#7
Mine goes up to 8.2. Chem geek has told me that if you don't have metals in the water, there is no issue maintaining a high PH. Since its really only necessary during very cold weather, once it starts warming up your CSI will want a lower PH more suitable for swimming without having to adjust your other numbers.
How do you get a test result of pH being at 8.2?

What are the metals to be aware of? The city water here is soft and salty and tastes like ****, but does have some amounts of stuff in it.
 

chem geek

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Mar 28, 2007
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San Rafael, CA USA
#8
It's mostly iron that would be in well water. If there are older copper pipes, then there may be copper as well. If the amounts are at 0.3 ppm or lower, I wouldn't worry about it, but if they are higher then you can get some metal staining at the higher pH.
 

eqbob

Well-known member
Jul 26, 2012
436
0
Central Texas
#9
From the most recent drinking water report, copper is stated to be at .112 ppm. Iron wasn't reported. Interesting to note that TA was reported at 432 ppm.
Except for the light and the screws around the water intakes, there is no metal in the pool.
 

graler

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Jul 18, 2014
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Cedar Park, TX
#11
I am glad I read this note. I was going to head to the store for acid today because the PH was high. What will I do with the free time now?

Thank you guys for all of the info on this site.
 

duraleigh

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#14
Well, the upshot of this could easily be construed that...

1. Operating outside the parameters of 7.2 - 7.8 is just fine - Not really. TFPC is all about simplicity and making pool water management easy for everyone. Keeping your pH within the TFPC guidelines will keep your pool happy and your life simple

2. Calculating CSI and LSI is an important part of everyday pool management. Not at all. I have never calculated either in my life nor do I intend to. CSI is so rarely important that there is virtually no reason to give it thought as long as your test results indicate that you are within the standard guidelines that TFPC suggests
 

zethacat

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Sep 23, 2013
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Dallas-Ft. Worth Metroplex, TX
#15
It's mostly iron that would be in well water. If there are older copper pipes, then there may be copper as well. If the amounts are at 0.3 ppm or lower, I wouldn't worry about it, but if they are higher then you can get some metal staining at the higher pH.
I think we established that my city may use some well water in the summer, which has some iron in it, but during the summer I won't be maintaining a high PH so it shouldn't be an issue for me.. unless the iron stays in the water and then when the water gets cold, it will come out of suspension from the high PH. That would be kind of worrisome... though I probably don't even need to think about that until next fall.

We do have some pretty sh*tty water here in north texas, but my TA and CH are very stable. They have barely moved at all since I filled the pool, and only because I raised them myself.

I would be more worried about fertilizer with iron blowing into the pool from the neighbors yards... and I also have to think about what kind of fertilizer I want to use myself. If I had to choose between a dead lawn or stains in the pool, I choose dead lawn. I have not fertilized my lawn at all since the pool is done.

I have some brown spots on my plaster that have been there since the pool was filled. I haven't noticed any additional ones, and the ones that are there seem to be fading but very very slowly. I am thinking if I drop my PH to 7.5 when I add acid, since it will only be at that a potentially corrosive level for a day or two, it may actually help with that without doing any damage to my plaster. Opinions?
 

zethacat

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Sep 23, 2013
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Dallas-Ft. Worth Metroplex, TX
#16
1. Operating outside the parameters of 7.2 - 7.8 is just fine - Not really. TFPC is all about simplicity and making pool water management easy for everyone. Keeping your pH within the TFPC guidelines will keep your pool happy and your life simple
Well am I on the right track with what I've been doing or do you think letting PH get to 8.2 (which is a 0 CSI for me) is too dangerous? Like I said, it's a .1 increase per day, so I am pretty confident that when I read 8.2 it's got to be very close to that #.. I do test daily.
 

eqbob

Well-known member
Jul 26, 2012
436
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Central Texas
#17
Well, the upshot of this could easily be construed that...

1. Operating outside the parameters of 7.2 - 7.8 is just fine - Not really. TFPC is all about simplicity and making pool water management easy for everyone. Keeping your pH within the TFPC guidelines will keep your pool happy and your life simple[/COLOR

2. Calculating CSI and LSI is an important part of everyday pool management. Not at all. I have never calculated either in my life nor do I intend to. CSI is so rarely important that there is virtually no reason to give it thought as long as your test results indicate that you are within the standard guidelines that TFPC suggests


#2 is probably an easy assumption to make considering pool math caculcates it and articles in pool school reference it, particularly in relation to scaling. I had scaling problems in the past but none since taking over the chemistry myself and watching the parameters as well as the indices. My question was based on the significant impact of temp on CSI and should it be counteracted by adjusting other parameters. Your answer for #1 would indicate no, keep the other parameters the same, which makes sense given what else can really be adjusted.
 

duraleigh

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#18
Well am I on the right track with what I've been doing or do you think letting PH get to 8.2 (which is a 0 CSI for me) is too dangerous?
People test at different frequencies and levels of understanding. Some people test everything daily and, unfortunately, some folks hardly test at all. We can't control that so we have to supply a set of guidelines that catches the most amount of folks.

So there is nothing inherently wrong with calculating csi as you choose to do. I am saying there is virtually never a need to and most people like this simpler approach.

Likewise, keeping your pH in the 7's at all times works just fine year round for virtually every one and allows a less intense approach to water management.