Can water chemistry affect pool plaster ?

JcSparky

Bronze Supporter
Aug 26, 2014
51
Baton Rouge, LA
Pool Size
7600
Surface
Plaster
SWG Type
Pentair iChlor 15
The weight of the water helps hold the pool in the ground. Drained pools have popped out of the ground due to pressure of the ground water.

We have a water exchange process that can exchange pool water for fresh water without draining.

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Makes sense, thank you. So my pool water is 78F and fill water is 75F, not that much difference. Where do you recommend the sump pump be (deep or shallow) and the fill water be (deep or shallow) ? It will be raining here over the next couple of days, so I imagine the pool temp will drop a few degrees.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,060
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Makes sense, thank you. So my pool water is 78F and fill water is 75F, not that much difference. Where do you recommend the sump pump be (deep or shallow) and the fill water be (deep or shallow) ?

I let @mknauss explain that. He has the complexities down solid.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,321
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
As your pool water chemistry is pretty benign (low CH, no direct salt addition) I would base it on the water temperatures. So add water to the deep end and pull off the surface (shallowest step is good).

Your efficiency will not be great so go at least 10% over volume during the exchange.
 
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JcSparky

Bronze Supporter
Aug 26, 2014
51
Baton Rouge, LA
Pool Size
7600
Surface
Plaster
SWG Type
Pentair iChlor 15
For those asking about possible pool leak, according to attached photos showing a 24 difference, it doesn't appear that I have a leak. Auto fill was turned off during this time as well.
 

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JamesW

TFP Expert
Mar 2, 2011
28,209
Ok. I guess it's a mystery how your pH can be 7.8 after 3 years of nothing but tabs.
 

JcSparky

Bronze Supporter
Aug 26, 2014
51
Baton Rouge, LA
Pool Size
7600
Surface
Plaster
SWG Type
Pentair iChlor 15
As your pool water chemistry is pretty benign (low CH, no direct salt addition) I would base it on the water temperatures. So add water to the deep end and pull off the surface (shallowest step is good).

Your efficiency will not be great so go at least 10% over volume during the exchange.
Thank you. I will attempt a pool water exchange over this week following the previously stated guidelines.
 

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JamesW

TFP Expert
Mar 2, 2011
28,209
The new pictures look like there are copper stains on the plaster, but it might be the color of the plaster.
 

JamesW

TFP Expert
Mar 2, 2011
28,209
The pH and TA readings are not possible if only tabs were used.

We're missing some relevant information.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,321
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
We're missing some relevant information.
Could those 4n1 tablets have baking soda or sodium carbonate in them? 6% other ingredients that I cannot find what it is.
 

OrangeAndBlue

Silver Supporter
Aug 19, 2017
111
Houston, TX area
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
How long ago did you get the TF-100 and how old are those reagents?

I just learned the hard way that reagents do go bad and will give poor results if not replaced regularly.
 

JamesW

TFP Expert
Mar 2, 2011
28,209
Possibly tetraborate, but it would not be enough to offset the acidity.

Based on a CYA of 260, the TA would have dropped by about 300 ppm.

Even if the tabs were 50% tetraborate, the TA would still be down by 140 ppm.
 

red-beard

Gold Supporter
May 27, 2019
1,395
Houston, TX
Pool Size
25000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite Pro (T-15)
Back on the possible "bad plaster job", look at the original photo and look at the plaster and the glass tile. That was not done at an expert level. I would say they is a possibility that this is a combination issue.
 

JcSparky

Bronze Supporter
Aug 26, 2014
51
Baton Rouge, LA
Pool Size
7600
Surface
Plaster
SWG Type
Pentair iChlor 15
How long ago did you get the TF-100 and how old are those reagents?

I just learned the hard way that reagents do go bad and will give poor results if not replaced regularly.
I was wondering when someone was going to ask that question. They are a year old and will replenish soon. I was thinking this could be causing my numbers to be wacky.
 

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