I haven't seen seen cracking from freeze thaw cycles and travertine but have seen slipperiness from some unsealed tiles. I am not saying it can't happen. The number of decks in my region though doesn't provide enough of a sample for me to say that but that the several I have seen haven't had this happen since I saw them.

I have never seen fences affected but have seen softer stone soak in water into pores and small cracks have issues, salted and non-salted alike. Harder rock materials such as fired brick and concretes used for paver style coping seem to fare far better.

Salt is not corrosive, in and of itself. Look a the metal cap on your salt shakers. Once you add water though, one of the chemical property changes is that the water can now conduct electricity, something pure forms of either couldn't do before.

Electricity is the flow of electrons between two points. That electricity can originate from more than one source. Often, cells get the blame and sometimes that is correct but for the most part, it isn't. It can come from a bad ground leaking a small amount of electrons or a broken or non existent bonding system. If the soils around the pool have differences in potential with the pool shell and water, a battery (think "D" cells for a flashlight) can form naturally. Occasionally, leakage from a cell can happen.

This can also be seen a little more quickly with metallic ladder and rail cups acquiring calcium deposits on an unbonded pool. Chrome sometimes looses it's luster too and stainless steel can form pits.

This can often be stopped by adding a well grounded or bonded zinc anode to the flow of water. Zinc is a less noble and inexpensive metal that will tend to attract any stray currents. It will sacrifice itself and won't add anything to the water that is bad. Keeping them clean keeps the zincs, as they are called, working. They will often last 5 years or more before needing replacement. Sometimes, two may be needed, one by the equipment and one in the skimmer or auto-fill.

Note that the flow of water and the flow of electricity are independent of each other. Water may flow left to right for example and electricity may flow right to left.

Also note that added salt is not the only thing that can make water conduct electricity. The addition of a number of minerals that a pool comes into contact with can and will add the conductivity of electricity to it, even some bird poops.

This makes the use of proper materials during construction all the more important. I have refused to install salt cells because the client would not sign a waiver absolving me when I tested the pool's bonding and it failed. I don't like it since it costs me money but I also don't want to have to defend myself which could cost me even more. This is the largest stigma many builders are concerned with.

That's not to say a particular material should not be used in the construction of a pool, but when covering your tush, well, it's just jurist prudence.

Scott

Thanks so much for the detailed explanation, Scott. Is there a newer system that has lower chlorine levels that would be a better alternative than salt?

Nope. Chlorine levels don't really change much regardless of how its added, whether on uses liquid, tabs, cal-hypo, dichlor, or lithium based powder. As long its about 8% of the stabilizer (CYA) level for free or available chlorine and the combined or spent chlorine level is less than 0.5 ppm, the chlorine level is good to go.

Each type of chlorine, though, may add something you don't need or want in the water. For example, dichlor powder and trichlor tab will add CYA, aka stabilizer and you may already have enough. Cal-hypo may add calcium and that may at the level desired. Liquids such as 12% sodium-hypochlorite or Clorox (6% sodium-hypochlorite) will add salt but that is usually pretty benign as is lithium hypochlorite (expensive though).

Some people profess silver and copper ions but the risks are not worth me blessing their use. Some people let the levels get out of hand and then let the pH bounce in either direction and the result is stains in or around the pool and blonds and whites we wear going green from the copper or black from the silver (rare but not unheard of).

Chlorine levels in pools is not something a well kept pool need worry about. Poorly kept pools are and are usually immediately evident. I have never met anyone allergic to chlorine. When your eyes hurt near a pool, it's due to spent chlorine, chlorine that did something like kill a bio-baddie or oxidized tanning lotions and is in a large enough amount you can smell it and feel it with your eyes. That is saying it's time to shock the pool.

Th stabilizer level for cells is higher due to the way it is produced and introduced. This keeps the cells ON time at a minimum. Most cells are good for about 10,000 hours of On time, time they are making chlorine (as well as some other stuff like lye that raises your pH and hydrogen). Less ON time equals a longer life.

Different regions also need differing amount of CYA for cells. In my region, 60 to 80 ppm is usually good but in the Florida Summer sun, a level closer to 100 may be called for.

Adding chlorine using any other method usually likes CYA under 50 ppm, with 30 in my area being the max norm.

Scott

Rochelle,
I feel your pain with the PB's. You would think that with the economy the way it is that it would be easy to hire a company and get work done. But it doesn't seem to be the case.
Regarding the freeze/ thaw cycles of travertine...
We do about 90% of our pool projects with travertine in Virginia and have never once had a problem with cracking or damage. :: Knocks on wood ::
I know that travertine is able to hold it's own in cold conditions. The problem sometimes lies in bad installation, or hiring a contractor that has never worked with it before.
As one of your PB's said, tumbled travertine is porous, and it's the only thing you'd want around your pool as it absorbs water and, therefore, is not slippery.
During the cold winter months, travertine needs room to expand and contract with the freeze/ thaw cycle. If travertine is cemented, it could crack. So you do NOT want to cement travertine. The installers that we work with typically sand set the material and use a flexible bond (like Flex Bond or similar) on the outer borders to hold everything in place. (It also allows you to easily pick up a piece and replace it should something happen ((ex. - your neighbor spills red wine on your light travertine at your pool party)).
I also need to mention that the quality of the travertine is really important. A standard grade travertine has many holes and pores and is not as dense as a premium grade stone. You will most definitely have problems if you purchase standard grade.
We have bought travertine from Travertine Mart in Miami for years. They freeze/ thaw test their materials and the results are listed on their website. They sell mostly premium and premium select grade travertine. I think they have only one standard grade product, and it clearly states that. Good luck with the search! And let us know what you decide to do!

Here is a link that might be useful: Travertine Mart Website

Thanks so much for the replies, Scott and vabeachdesigner. I think I'm getting a better handle on the whole project with your help.