Do Salt Generators damage limestone/masonary

[chem geek]

Something we learned the hard way. We had our pool renovated 5 years ago. We had limestone used instead of tile/coping. We have been having ongoing problems with the limestone flaking, cracking, etc.
One day talking with a stone dealer (for something else, they did not supply stone for pools) I found out there are different "grades" of limestone. The cheaper grades act as the limestone in our pool (which I have been using tri-chlor pucks, bleach only so far).
Anyway, I am no expert but just thought I would pass that on.

So this would indicate that the quality of limestone is a primary factor since your pool is not a salt pool (no SWG). Technically, even non-SWG pools have salt in them, of course, but generally it starts at around 350 ppm (the sodium from the bicarbonate and the chloride from the calcium chloride, plus some more chloride from muriatic acid) but usually stays below 1000 ppm with regular dilution from backwashing.

Just to be sure, do you have a DE or sand filter that you regularly backwash or do you have a cartridge filter and yet manually drain and fill part of your pool water? I'm just trying to get a handle on the salt levels in your pool.

Richard

[craiga]

My un-educated theory? Limestone varies in hardness based on the quarry, hardness of the particular seam being mined, ect. Leuters limestone (which is what my coping is) is from a quarry in Leuters Texas that is known for limestone that is particularly hard. However, limestone is a natural product and therefore somewhat un-predictable. The coping stones around my spa are larger stones than the rest of the pool. My guess is that the larger (spa) stones were mined from a different seam than the rest of the pool. The pool stones were probably mined from a seam that had a stretch of soft stone in it. I probably got that batch of stone that is too soft to be used as coping. For that matter, who knows if the stuff really came from Leuters. The name has become analagous with hard stone and a stone vendor can call any stone Leuters and who would know the difference? Just my therory, but i know that a lot of limestone, for instance the flagstone on my deck, is soft and flakes, and would not be suitable for use as pool coping. So, I am going to have it replaced and will apply the best sealer i can find, but based on what i have learned here, the salt water generator is irelevant as to whether it will detoriorate or not.

[fofa]

Just to be sure, do you have a DE or sand filter that you regularly backwash or do you have a cartridge filter and yet manually drain and fill part of your pool water? I'm just trying to get a handle on the salt levels in your pool.

I have a DE filter and backwash as needed (via pressure readings).

[chem geek]

I have a DE filter and backwash as needed (via pressure readings).

Thanks. So your salt levels in your pool are probably in check and well below 1000 ppm. That would make the quality of the stone the dominant factor in your corrosion. So "craiga's" pool builder shouldn't be using the fact that a pool has salt or an SWG as an excuse for what may be poor quality stone.

Of course, the problem is that there may be times when higher salinity is indeed a problem especially with certain types of stone and yet this whole issue gets muddled as fingers point to whom to blame. And there are other times when not using CYA, with the result being very high disinfecting/oxidizing chlorine levels, may be the primary source of corrosion (a possibility in this thread).

Richard

[Poolsean]

And yet, salt gets the blame.
I think since it's the newest (not really) guy on the block, it gets the brunt of the blame. The problem is that for many years, limestone and decks have gone through the same damage problems, but what did they blame back then?
Bad batch of cement, calcium, aggregate, sand, water quality, etc. Believe me, after 20 years in the pool industry, I've heard all these. So now that salt systems are becoming more popular, let's blame them!

What's important to note is that these same issues occur on pools without salt systems.

Salt damage? How long do seawalls last before the sea water, which by the way is on average, 10 time greater than a salt water pool, starts to show damage it? Hmm, me thinks a good number of years! I can't recall when the City of Ft Lauderdale had to rebuild the "Wave Wall" along the beach boardwalk. I grew up in South Florida, 15 minutes from the beach, and the same seawall that I fished off of 35 years ago, is the same one that I fish on today. Awesome snook fishing by the Haulover Beach area!
So how does a pool deck delaminating after a few years mean that the salt system is the cause?

Richard, by the way, it is typically a bleach pool that shows a higher level of salinity when maintained this way for 3 or more years without any significant water exchanges. Tab and cal hypo pools are usually minimal in salinity, less than 500 ppm.

I may be defensive on this issue because there are so many "old school" pool service guys and builders that refuse to come into the 21 century. Salt systems for them is just something new to learn about and takes them away from what they've known and done for years. Not knowing about salt systems mean loosing accounts, so it's in their best interest in speak badly about salt systems.
In the 20 years of dealing with salt systems, guess how many deck damage issues I've had to deal with in South Florida? ZERO.
While I've heard of such conditions, I have not seen such conditions that were directly accountable to a salt system.
Staining from salt, sure I would admit to that occuring with certain salts.
Corrosion from salt, sure I would admit to high chlorine or over salting a pool causing a certain level of corrosion damage.
Electrolysis? yeah, if the pool isn't bonded properly, installed correctly, or there's an electrical grid issue, there may be stray voltage introduced into the pool due to a salt system.

Sorry for being long in my response. I think I'll take this up in the China Shop.