Disintegrating Stone Work

[Wungee]

Hey Folks,
As you can see, this is my first time posting. Also, I am new to pool ownership. My wife and I bought our house 4 months ago, so there's been a bit of a learning curve trying to care for the pool. Of course I hired a "pool person" who comes out weekly, and so far I am happy with their service. Anyway, my concern is that the stone work around part of the perimeter has an area where the stone seems to be dissolving. If I don't touch it is fine (maybe) but if I aim a water hose at it, or just touch it with my hand, it starts to crumble a bit (it almost feels like sand). I asked my pool "expert" but he only knows about maintaining the water and the pumps; this is more of a construction issue. So I am wondering two things:

1) Should I am a hose at the stone work to remove the top crumbly layer? and 2) Should I apply some kind of "seal" to the stone work so that this doesn't continue? I see that Aqua Mix makes a "Seal and Finish" -- is that something I should try?

Thank you for your consideration.

Wungee

[Teapot1]

Without a photo I am at a bit of a loss, is it a concrete coping, a soft stone like travertine?