Sand stone sealant DIY

[EmmaApp]

We bought a house with a pool a couple of years ago. The (Texas) sand stone that makes up all of the visible coping and water features is really soft and porous and erroding away. It was (apparently) sealed the year we moved in, but I doubt it. We have constant sand in our pool from stone erosion.

Has anyone had similar issues?
What did you use?
How did you use it?
Did you need to prep the stone or drain the pool (oh God help me)?

All suggestions welcome

 

[EmmaApp]

Also Silicone or Water-Based???

 

[Tena]

Also Silicone or Water-Based???

Did you find a solution? Ours is brand new. I didn't want it, but PB insisted. I know it wasn't sealed and if you rub a paper towel on it is always brown.