First I would make sure that all the moisture has escaped.  I would than try a mild acid such as sulfamic acid in a test spot.  Its common for water to leave mineral stains behind. be careful not to let the acid dwell too long since it will compromise the surface.

On Thu, May 24, 2018 at 8:28 AM, Barry Raduta <barry@diamondstoneandtilecare.com> wrote:
Hello Partners,
Thank you in advance for helping me to discover a remedy for this situation.  I have a friend who owns a hardscaping company who installed "tabby stone" as a pool deck.  Tabby is a cast concrete with oyster shells in it.  As you can see from the photo, many of the tiles have retained water marks around the edges and will not go away.  Grout has not been installed yet.  Is there a cleaner/solution that can be used to get the stains out using a nylon brush on a floor machine.  I don't have much experience with outdoor projects.
Thanks,
Barry
---------- Forwarded message ----------
From: <stonerestorer@gmail.com>
Date: Thu, May 24, 2018 at 8:16 AM
Subject: IMG_2134.JPG
To: Barry Raduta <barry@diamondstoneandtilecare.com>







Sent from my iPhone



--
Thank You,
Barry V Raduta
Diamond Stone & Tile Care-South
Stone & Tile Pros
843-540-1445


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