Problem with limestone coping and a salt water system

Longboat58

Bronze Supporter
Jul 6, 2019
17
Austin, TX
Our pool was built 15 yrs ago with coping from a local limestone quarry and a salt water system. Within 1 year our coping started deteriorating. Basically it was pitting and flaking away. It took the builder a while to determine that it was the salt water system. Their solution was to replace the coping and seal it. However, within another year it started happening again! So they gave up and replaced the coping again and switched our pool to a standard in-line chlorine feeder. (Supposedly they could not switch us to a stone coping because of the thickness.) Since then we have not had any issues. They thought that since limestone is porous the salt water was seeping into the stone and once the water evaporated the salt would crystallize causing the stone to slowly break apart. I don’t know if that is what was happening but it appeared that the salt was the issue. Thirteen years later and we are still good. Maybe some limestone is more dense and it wouldn't have been an issue but I wanted to share our story of what we experienced. We were lucky that the builder honored their warranty and took care of it but it was a real pain. Here is a link to a picture of one of the pieces. Limestone piece
 
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Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
19,810
Bedford, TX
58,

I think they just kept replacing the limestone until they got some good quality stone. The salt in a saltwater pool is about as salty as your tears..

I know of no scientific evidence that proves your point.. I also don't know of any scientific evidence that proves my point, so we will just have to agree to disagree. :mrgreen:

I have the opposite story.. I have a rent house pool where we put down flagstone coping.. It was a non-saltwater pool and within a year the coping was shedding layers of sand... Some stones were just fine, but others were shedding.. Often, the good and bad stone were right next to one another.. After about two years, we switched to saltwater.. That was roughly about 7 years ago.. Today, the bad stones are still bad, and the good stones are still good.. At least in my case the saltwater did not cause the problem and has not seemed to make the problem any worse.

You don't still have any of that lime stone left over do you??? It would be interesting to do some experiments..

Thanks,

Jim R.
 

Longboat58

Bronze Supporter
Jul 6, 2019
17
Austin, TX
Hi Jim,

Thanks for your feedback. I wish we knew for sure because we liked the SWG. But it seems odd that splash water alone could cause such damage twice, each time within 1 year. I assume all three batches of stone came from the same quarry. I would think that if pool water alone (no salt) could cause this due to poor stone quality that the pool builder (a national company) would've known that was possible and would have experienced it long before but evidently that was not the case. I am guessing that they had not been using SWG long and just didn't know what would happen.

But yes I still have lots of the old coping as we used it in some landscaping.

Thanks again, Russ
 

jorge18

Well-known member
May 2, 2018
199
Miami, Fl
I have to agree with Jim, the amount of salt a SWG uses is quite minimal. I don't think it's enough to eat through limestone.
 

Longboat58

Bronze Supporter
Jul 6, 2019
17
Austin, TX
Something else to consider. As I mentioned earlier, we used a lot of the removed coping in our landscape and the deterioration stopped even though it has been exposed to rain and water from the sprinkler system. So it would seem that it must have been something other than just water that caused the deterioration.
 

mguzzy

Gold Supporter
Jul 8, 2015
2,425
OV, CA
I don’t know if that is what was happening but it appeared that the salt was the issue. Thirteen years later and we are still good. Maybe some limestone is more dense and it wouldn't have been an issue but I wanted to share our story of what we experienced.
hmm.. So when you stopped using the SWG did you drain your pool to get the salt out? Or was it still a salt pool and you just stopped using the SWG for chlorination? And I wonder how the builder determined it was the salt that was the culprit. What was his reasoning? I know that was 13 years ago, but I was just curious.
 

Longboat58

Bronze Supporter
Jul 6, 2019
17
Austin, TX
After the builder replaced the coping the second time, they drained the pool and removed the SWG and installed an inline puck chlorination system. We have had no further issues with the coping since then. The builder told us that since the limestone is porous the salt water was seeping into the stone and once the water evaporated the salt was crystallizing inside the stone causing the stone to break apart.
 

Exlonghorn

Gold Supporter
Jun 16, 2019
84
Houston
Our pool was built 15 yrs ago with coping from a local limestone quarry and a salt water system. Within 1 year our coping started deteriorating. Basically it was pitting and flaking away. It took the builder a while to determine that it was the salt water system. Their solution was to replace the coping and seal it. However, within another year it started happening again! So they gave up and replaced the coping again and switched our pool to a standard in-line chlorine feeder. (Supposedly they could not switch us to a stone coping because of the thickness.) Since then we have not had any issues. They thought that since limestone is porous the salt water was seeping into the stone and once the water evaporated the salt would crystallize causing the stone to slowly break apart. I don’t know if that is what was happening but it appeared that the salt was the issue. Thirteen years later and we are still good. Maybe some limestone is more dense and it wouldn't have been an issue but I wanted to share our story of what we experienced. We were lucky that the builder honored their warranty and took care of it but it was a real pain. Here is a link to a picture of one of the pieces. Limestone piece
I installed a SWCG about 8 months ago (pool was installed in 2010 as a non-salt pool). Within the past 8 months, the stone coping around the edge of the pool and spa is showing significant signs of deterioration...flaking, chipping, etc. That leaves little doubt that using a SWCG will degrade some types of stone fairly quickly. I'm going to put down a salt water resistant stone sealer as soon as we have three days of clear weather (which looks like it may take a week or two!)
 

Longboat58

Bronze Supporter
Jul 6, 2019
17
Austin, TX
I installed a SWCG about 8 months ago (pool was installed in 2010 as a non-salt pool). Within the past 8 months, the stone coping around the edge of the pool and spa is showing significant signs of deterioration...flaking, chipping, etc. That leaves little doubt that using a SWCG will degrade some types of stone fairly quickly. I'm going to put down a salt water resistant stone sealer as soon as we have three days of clear weather (which looks like it may take a week or two!)
Good luck with the sealer! Our builder tried that the second time around but it did not help. Of course they may not have applied it properly or used the correct type but it's sure worth a try. What type of stone do you have? Thanks