what is this pool deck stain and how to remove??

4 replies [Last post]

Hi everybody,

I'm hoping someone here can help me with this problem.

I installed a textured splatter finish on a pool deck  a few months ago and I got an email from the homeowner last week with an issue that has arised.  There is a stain that they're having a difficult time removing.  It's white in color but dos'nt look at all like blushing.  I've uploaded this picture so that perhaps somebody on this forum can shed some light.  the rest of the deck I was told looks good.  It's just this area.

The pool is a salt water filtration type pool.  Thanks for your help on this as in all the years I've been doing this type of finish I have never enountered this.



Lindy A.'s picture
Lindy A.
What you are seeing is salt

What you are seeing is salt stainig and "whitening" caused by the salt water pool.  If the swimming pool water is above 2800 ppm (often you will find salt water pools to be in the 4,000 to 5000 range) it will take a toll on cementatiou surfaces, decorative concrete of various types, and typical sealers that do not have the required degree of chemical resistancy necessry to shield and protect them from exposure to corrosive conditions.


When the salt water from the pool is splashed out on the deck, it can accumulate or puddle in random areas.  The salt will dry on the surface as the water evaporates, etching and discoloring the deck/surface.  Although salt water may not be considered aggressive while contained in the pool itself at 3000-3500 ppm ... when it puddles or acculates on a deck it will leave a pure salt residue behind that is very corrosive.  In Caifornia there is currently and evironment movement referred to as "ban the brine." 


Think of this salty pool water, with the salt residues being left on th surface after the water has evaporated as being in the same/comparable corrosive family (in relation to damaging concrete, decorative concrete, and many types of sealers) as when salt is used for deicing purposes in northern environments ... both can and will take a toll (in the form of discoloration and etching; along with other cosmetic issues).


Your customer needs to be instructed to hose down their pool deck with plenty of fresh wtaer EVERY time they use it in order to flush all the salt water off of it.  They also should strive to keep their salt water no higher than 2800 ppm.


At this point in time, the damage is done (I doubt it can be reversed).  I read somewhere that hot vinegar will break down the salts and sometimes remove the salt staining and "whitening" caused by the salt residues left after evaporation takes place (on ordinary concrete); however, I would not blindly try this on the pool deck since I don't know how it would effect your stain & sealer.  You might be able to scrub with CLR to remove some of this discoloration; it might help camoflauge the problem (cleaning it to some underminable degree), but this too is very doubtful, depends on the degree of damage that has been done. 


I believe your only solution will be thoroughly clean the surface, then apply a sealer that has been tinted to restore the pool deck to a uniform color.  It would need to either be compatible with the one you applied initially (although the problem will occur again if the pool owner does not keep their salt water in the 2800 ppm area and if they don't hose the deck down after EVERY time they swim with plenty of fresh water to remove all the salt water that was spashed or dripped on the the deck) ... otherwise you will need to strip the sealer on the surface before you reseal..  Of course, you could eliminate the problem in the future by applying a highly chemical resistant sealer on the pool deck (in all likelyhood you would need to strip the sealer you applied first due to compatibility/bonding issues), capable of shielding it against attack by corrosive salt water environment (if you have questions/concerns about high performance sealers (capable of survival), please feel free to give me a call or drop me an email message).


Lindy A.

Get your water tested

Get your water tested regularly by providing a sample to a pool supply store or swimming pool maintenance specialist. Test the water yourself on a regular basis by purchasing a testing kit that will help determine the pH balance level of your water. Use high-quality chemicals and tools in the maintenance of your swimming pool.

Swamizu's picture
Actually, some pool owners

Actually, some pool owners find that using vinegar, along with a wet vac, is effective. However, Lindy is right about it's effectivity.

Applying sealer is the best solution and expect that you will do this over and over again. Salt is concrete's worst enemy  and there’s little you can do to completely stop its effects. Some salt water pool owners cleverly paint their pool decks to conceal the salt residue making the stain unnoticeable. Pool paint can actually withstand salt's effects to pool decks.

In a nutshell, pool maintenance is the best prevention. If you consider repainting your pool deck you can visit our pool paint section and have a professional to back you up.

Good luck!


Lindy A.'s picture
Lindy A.
Swamizu ... your interaction

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Lindy A.

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