Opinions on whether salt will damage the stone on my hot tub waterfall?

[gtty]

Does anyone have an opinion whether converting my pool to SWG will damage the flagstone on the hot tub waterfall?

 

[ajw22]

My opinion is a SWG will make no difference if your flagstone is damaged over the years.

 

[Jimrahbe]

Gtty,

Flagstone is not what I would have used on a waterfall.. It is basically compressed sand...

The good or bad news, is that it will wear the same with, or without, any salt in the water..

My daughter had an old pool replastered, new waterline tile and flagstone coping.. The installer was adamant about not going with a saltwater pool.. For the first 3 or 4 years the pool was a standard Chlorine tablet pool, adding weekly doses of 'shock'.. Within the first year, some of the flagstone was flaking apart. There were good stones and bad stone right next to one another.. The sand would fall into the pool and was picked up by the robot cleaner. About 12 years ago we converted to a saltwater pool... Nothing changed.. The bad stones are still bad and the good stone are still good. In fact, over the last two year, the sand that was getting into the pool has stopped.. I doubt that has anything to do with the saltwater, I think the flagstone just got tired...

As far as I can tell, the thickness of the flagstone has not changed much.. maybe a 1/16th of an inch max...

My point is.. you either have good flagstone or not.. the saltwater is not going to make any difference..

Is this an old pool or a new pool???

Thanks,

Jim R.

 

[.ben]

A forensic engineer once told me flagstone should never be used around a pool (remark was specific to Houston area).

My opinion is that a slightly elevated salt content won’t make a difference whether you eventually have problems, or not.

For what it’s worth, I would never own a pool in Houston without a SWG.

 

[TinFoilHat]

All pools will eventually become salt pools to some extent just from chlorine use.

 

[gkw4815]

Another vote for the SWG from a Houston-area pool owner. It makes maintaining the pool during our brutally hot summers both easier and cheaper. A couple of notes from my experience:

-My pool is almost 30 years old and has been operated as a saltwater pool for about half that time (original owner installed one during the build, and abandoned it after the second or third cell failed. I installed a new SWG system a couple years ago). My pool shows no signs of undue wear or degradation; in fact, the opposite is true (plaster is original and is still presentable, stone coping in good shape, 2/3 pool lights are original and still working well).
-When I tested my water prior to SWG startup my salt was over 2000 ppm...as everyone else says, all pools are salt pools to some extent.

 

[Jaimslaw]

Couldn’t agree more with the flagstone wearing irrespective of having a SWG or using tablets. Each stone varies in density such that some will withstand virtually anything you throw at it while others will go into the flake stage that never flakes, never ceases to flake, or decreases as the stone flakes to a denser part of the stone. I have a stone on one side facing the pool at the spa spill over location that has never stopped flaking over the last 20 years . . . and at some point, I”m going to have to deal with its replacement. Not looking forward to that project.

 

[Dirk]

All pools will eventually become salt pools to some extent just from chlorine use.

Beat me to it. Chlorine, muriatic acid, and humans, (sometimes even fill water) all leave salt behind after they do their thing. Since that salt doesn't evaporate with the water each day, it just builds up. So all pools do, indeed, become saltwater pools. Only splash out and water exchanges (including rain) reduces the salt level. Unless you regularly exchange a lot of water, your chlorine pool will be just as salty as your SWG pool. Might as well put that salt to use so that you can enjoy the convenience of an SWG!

And as @Jimrahbe describes, that is exactly what I experienced. The pool I inherited was a chlorine pool for many years. It came with a sand-covered, flaking flagstone coping. The design has about a dozen spokes of flagstone that radiate out from the coping, plus a flagstone patio nearby. I have the perfect flagstone testing ground! It's more than obvious that all the sanding and flaking is happening near the pool water. Not to the spokes. Not to the patio. The patio and the spokes are like new. Some of the coping stones are untouched, others are rougher (from the erosion) and a few are badly pitted. The worst stones are those by the steps, which get wet much more than any of the others.

When I installed an SWG, nothing changed, just as Jim described. That's proof to me that (1) flagstone is a very poor choice for coping*, and that (2) the wear and damage is caused by the pool water, but that wear and damage has nothing to do with my SWG.

I also very much doubt the problem has anything to do with salt. It's the water. Just ask the Grand Canyon! And since an SWG allows you to maintain a slightly lower FC level, therefore introduce LESS chlorine, if anything, it could be argued that an SWG is BETTER for a flagstone coping.

Moral of the story: use an SWG, don't use flagstone.*

I also know that some types of flagstone are better than others for a pool. Even some pieces of the same flagstone are better than others. But I have no idea how you figure out which is which during a pool build.

*All that said, if you have flagstone that is deteriorating, there is a treatment that will all but eliminate the ongoing damage. I had it done. It works great, but is crazy expensive. And it is not stone sealer, that won't solve the problem. If you need the treatment... inquire within and I'll explain further.

This pic shows a few of the spokes I was describing, and you can see some of the extra damage near the steps, and how the spokes and some coping stones are just fine:



Now all that said, I absolutely LOVE my flagstone coping. I didn't choose it, but I might have. I love its organic look and the color. If I ever have to replace it, I'll really miss it if I can bring myself to use something else. More than likely, when the time comes, I'll just replace the worst stones and stick with the flagstone. I'll just treat the new stones, and re-treat the rest. Which is what should have occurred when the pool was built. It's what all flagstone owners should consider, before the wear gets too bad.

 

[Dirk]

My friend @mcleod* was the one who applied the treatment to my coping. He can weigh in about what he did, why what he used is the correct solution (and not just sealer) and about flagstone in general, including any warnings about saltwater.

*Stone restoration and protection is a core expertise of his company.

 

[JJ_Tex]

How old is the pool and do you see any flagstone damage/flaking already?

I agree with others that the minimal increase in salt will have no impact on the flagstone, but if you are still under warranty I guarantee 100000% that your builder would use that against you. If you are not under warranty and not seeing any flagstone flaking (consider yourself lucky), then I say go for it with the swcg.

 

[mcleod]

My friend @mcleod* was the one who applied the treatment to my coping. He can weigh in about what he did, why what he used is the correct solution (and not just sealer) and about flagstone in general, including any warnings about saltwater.

Stone restoration and protection is a core expertise of his company.

Morning.
I was hibernating. The process is called consolidation. A chemical molecular structure binds to the mineral(s) in the stone, creating a web or matrix that strengthens the stone. It can be used with a sealer (some products already incorporate it). On @Dirk, we used Prosoco OH100 Consolidating treatment. Good company, good product. However,
to fully cover your posterior, the company offers a testing and recommendation procedure ($$) to determine appropriateness and the application procedure. OR find a contractor VERY familiar with the product. Said contractor will likely be able to guesstimate when the process is complete (this was the case for @Dirk)

AVOID SEALERS on the stone at the point of the waterfall. Water-repellent sealers will change the surface tension and could later affect the water flow over the rock, possibly spoiling the aesthetics.

I think the advantages of an SWG outweigh the disadvantages.

McLeod

 

[gtty]

Gtty,

Flagstone is not what I would have used on a waterfall.. It is basically compressed sand...

The good or bad news, is that it will wear the same with, or without, any salt in the water..

My daughter had an old pool replastered, new waterline tile and flagstone coping.. The installer was adamant about not going with a saltwater pool.. For the first 3 or 4 years the pool was a standard Chlorine tablet pool, adding weekly doses of 'shock'.. Within the first year, some of the flagstone was flaking apart. There were good stones and bad stone right next to one another.. The sand would fall into the pool and was picked up by the robot cleaner. About 12 years ago we converted to a saltwater pool... Nothing changed.. The bad stones are still bad and the good stone are still good. In fact, over the last two year, the sand that was getting into the pool has stopped.. I doubt that has anything to do with the saltwater, I think the flagstone just got tired...

As far as I can tell, the thickness of the flagstone has not changed much.. maybe a 1/16th of an inch max...

My point is.. you either have good flagstone or not.. the saltwater is not going to make any difference..

Is this an old pool or a new pool???

Thanks,

Jim R.

This pool was here when we bought the house. I believe its over 10 years old.

 

[gtty]

Morning.
I was hibernating. The process is called consolidation. A chemical molecular structure binds to the mineral(s) in the stone, creating a web or matrix that strengthens the stone. It can be used with a sealer (some products already incorporate it). On @Dirk, we used Prosoco OH100 Consolidating treatment. Good company, good product. However,
to fully cover your posterior, the company offers a testing and recommendation procedure ($$) to determine appropriateness and the application procedure. OR find a contractor VERY familiar with the product. Said contractor will likely be able to guesstimate when the process is complete (this was the case for @Dirk)

AVOID SEALERS on the stone at the point of the waterfall. Water-repellent sealers will change the surface tension and could later affect the water flow over the rock, possibly spoiling the aesthetics.

I think the advantages of an SWG outweigh the disadvantages.

McLeod

thanks

 

[Hal3]

That's always the big scare. "If you have a saltwater pool it will destroy the rock around your pool."

I just say "Last time I was at the ocean shore the rocks looked just fine."

 

[jonpcar]

A question to those that have had SWGs longer than I have (6 months)….does salt build-up like calcium does? It looks like your pool already has a calcium problem around the tiles. Does the calcium also show dramatically on the walls under the “waterfall” when it is dry?

I’m very surprised that there is no overhang on the waterfall ledge so the spa spillover basically flows down the wall surface…probably designed that way and the look they wanted. However, I would think that design would be subject to sediment ( calcium, salt?) build up. If you haven’t seen that, than maybe nothing to worry about…has that stone veneer section of the wall been replaced?

 

[mknauss]

Salt dissolves instantly at the low level ppm your pool water is at. It will not ‘build up’