How to remove salt crystals & then protect bluestone around salt water pool

by Cliff McClinton
(Gadsden, AL USA)

We have a perimeter overflow pool with bluestone coping that has water flowing over it constantly. We have had no issues with this coping as it is not subject to wet / dry cycle and constantly stays wet. The Pennsylvania bluestone natural cleft squares that surround the pool is a nightmare. The stone has changed to a much lighter shade and appears to have delaminated in places. It was installed over a ooncrete base. The stone was never sealed Due to the overflow design of the pool saltwater always saturates the patio when we swim and when it rains.

1> What can we do to removed the salt crystals on the grout lines & and clean the stone so that it returns to its original darker blue color? The squares are darker in the middle and get progressively lighter around the edges. We have pressure washed the surface of the stone previously but this does not remove the crystals.

2> Should the top of the stone be sealed at this time? I have read many differing opinions on this from sealing all 4 sides of the stone and edges before installation to NEVER seal the stone as it will trap the salt into the stone.

3> What professionals handle this type of repair?

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Is Epoxy grout appropriate for use with Bluestone? NEW
by: Cliff Mcclinton

Our grout has disintegrated on our perimeter overflow pool deck due to all of the salt water from the pool and we have sawed out all remaining grout. I asked the guy that built my pool if there was another grout that would hold up better and he suggested an epoxy based grout. Is this appropriate? Our Bluestone was never sealed and I'm curious how difficult it will be to get the epoxy off the stone during cleanup. Any recommendations are appreciated.

definately seal
by: David

Dear Cliff,

With all of that moisture and saltwater flowing on your bluestone, you'll definitely need to seal the stone.

The water right now slowly drips into your stone and joints and causes efflorescence.

It's hard to tell how bad it's got from your pictures, but you might have to sandblast some spots. If you do, try it in one out-of-the-way spot and test it. You want to see if you get the desired effect before you do it to your whole slab.

However, before you do that, you should call Prosoco at 1-800-255-4255 and ask them about a solution for removing the white spots and also about a sealer for your situation. They might have something for you before you sandblast. You can also check out their products at:

Someone from this site recommended this product:

We've never used it so we can't say for sure whether it is good.

There is also another question about pools that many people commented on. There some info in it that might help you. You can read it here:

Great luck with your project!


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