Damage from saltwater in Pool

[march2012]

Moved from here.

What your PB is saying has no scientific basis that a pool st SWG salinity is any more damaging to a natural stone then a non-salt pool. And the kicker is that if you use Liquid Chorine, that has salt in it, in about 2 to 3 years the salinity will be the same as a SWG pool. Does your PB tell you to worry about that? Nah!

This has become the mantra on this forum, yet there is plenty of scientific evidence that ocean water concentrations of salt destroys stone.

How salt causes buildings to crumble

Salt crystals are often responsible when buildings start to show signs of aging. Researchers have studied salt damage in greater depth and can now predict weathering processes more accurately.

www.sciencedaily.com

The experiment showed that the greater the supersaturation, the greater the salt's destructive potential. Temperature also played a role: in cycles in which the temperature never fell below 25˚C, it took an average of four cycles before damage occurred. When the temperature dropped to 3˚C, one cycle was enough. "Although these wet and dry cycles play a part, supersaturation is the most important factor," explains chemist Caruso.

For a building, this means that if environmental conditions are such that a salt solution repeatedly infiltrates porous stone and the fluid can then evaporate again (e.g. due to strong sunlight or wind), the salt in the building material can become supersaturated. "In these cases, it doesn't take a lot of salt to inflict considerable damage," says ETH professor Flatt. However, higher amounts of salt are needed in more moderate environmental conditions.

 

[PoolGate]

This has become the mantra on this forum, yet there is plenty of scientific evidence that ocean water concentrations of salt destroys stone.

How salt causes buildings to crumble

Salt crystals are often responsible when buildings start to show signs of aging. Researchers have studied salt damage in greater depth and can now predict weathering processes more accurately.

www.sciencedaily.com

Saltwater pool concentrations are 3 parts per thousand. Ocean saltwater concentrations are 35 parts per thousand. HUGE difference!

 

[Newdude]

And the building materials / locations being discussed are pounded 24/7, like the pilings under a bridge. Occasional splash out is a joke by comparison.

 

[march2012]

And the building materials / locations being discussed are pounded 24/7, like the pilings under a bridge. Occasional splash out is a joke by comparison.

There are plenty of examples of buildings and statues that are only exposed to salt air or salt via rain. I didnt bother to post all the literature, just one summary study to emphasize the point that there is data that specifically shows that salt can destroy stone. Concentrations, temperature, time periods are all important.

This study used 6% and 2% concentrations (sodium sulfate, not chloride). this is roughly 15 times and 5 times the normal pool concentration of salt.

Chemo-mechanics of salt damage in stone - Nature Communications

Growth of salt crystals in pores is one of the most damaging weathering mechanisms for stone in ornamental structures and historical buildings. Here, the authors present a simple yet powerful treatment for predicting when salt damage will occur, quantifying this susceptibility to salt...

www.nature.com

From

How salt crystals destroy stone buildings

Scientists studying salt damage to buildings have found a way to predict the weathering process more accurately.

www.futurity.org

This damage caused by salt is not seen only on historic buildings. It is also a problem for wall paintings, such as Michelangelo’s frescos inside the Sistine Chapel in the Vatican, says Caruso. These can be damaged by salt efflorescence in the stonework or the paint layers or in between.

The researchers are now planning to use their findings in a project in Havana’s old town, where salt is a major issue. The special render used in restoration work crumbles away from building façades after just a few years, and the aim of the research project is to discover the exact cause.

 

[Newdude]

just one summary study to emphasize the point that there is data that specifically shows that salt can destroy stone

It can. And it does. But nowhere near the short timeframe of a couple of seasons that people report their patios weathering when blaming the salt pool. A lifetime ? Sure. 25 years even....... but not 2 years.

 

[PoolGate]

There are plenty of examples of buildings and statues that are only exposed to salt air or salt via rain. I didnt bother to post all the literature, just one summary study to emphasize the point that there is data that specifically shows that salt can destroy stone. Concentrations, temperature, time periods are all important.

This study used 6% and 2% concentrations (sodium sulfate, not chloride). this is roughly 15 times and 5 times the normal pool concentration of salt.

Chemo-mechanics of salt damage in stone - Nature Communications

Growth of salt crystals in pores is one of the most damaging weathering mechanisms for stone in ornamental structures and historical buildings. Here, the authors present a simple yet powerful treatment for predicting when salt damage will occur, quantifying this susceptibility to salt...

www.nature.com

From

How salt crystals destroy stone buildings

Scientists studying salt damage to buildings have found a way to predict the weathering process more accurately.

www.futurity.org

Those percents are actually 20 times and 7 times, but I get your point.

What you aren't taking into account is that saltwater pools and non-saltwater pools have roughly the same salt concentration after a few seasons. 2-3 parts per thousand. Everything you add to a pool chemical-wise adds salt. This includes chlorine and muriatic acid, the 2 most common additives. So to say saltwater pools are bad and "non" saltwater pools are not is a stretch. It should make one wonder of the reasons for the misrepresentation.

The main goal of those that poo poo saltwater pools due to the "destructive nature" of saltwater is to sell you an alternative system like Ozone, UV or mineral systems. Always look at the ulterior motives. Do your research and choose the system you feel the most comfortable with.

This site is a non-profit entity run by pool owners with no profit to be made by selling you pool care products. There aren't even any ads on the site. TFP is not a "general discussion" site about pools and what what one individual likes over another. TFP endorses 1 style of pool care and is dedicated to disseminating that proven method. Other methods are out there, but they are not the point of this site, and hence why this post was moved.

 

[pjt]

All pools are salt pools to one extent or the other. My liquid chlorine pool (non-SWG) had a salinity of 4,400 before I did a partial drain and fill. OBTW, there was zero indication of any sort of salt damage anywhere.

 

[zea3]

Water without salt is also destructive. Beautiful canyons have been carved into stone by centuries of river erosion.

 

[YippeeSkippy]

This study used 6% and 2% concentrations (sodium sulfate, not chloride). this is roughly 15 times and 5 times the normal pool concentration of salt.

That study should have used sodium chloride.
As we know, sulphates build up and destroy cement over time..... so we don't endorse the use of sulphate products such as "dry acid" in TFP pools.

 

[Katodude]

Water without salt is also destructive. Beautiful canyons have been carved into stone by centuries of river erosion.

Pure water is probably one of the most corrosive substances out there.

 

[chiefwej]

Pure water is probably one of the most corrosive substances out there.

No ”probably” about it, water is the closest thing to a universal solvent that exists.