Tiles falling off of inground Pebble Tec pool

[Phlimm]

I have an inground PebbleTec pool and at the stairs to the shallow side, we have lost three square tiles and one corner piece. They did not break, just fell off. We kept them to put them back on, but I don't know what to use to do so and how to make sure no more fall off.

Thanks a lot in advance, advice from this forum has definitely made a huge difference in the health of my pool.

[Xclusive]

What kind of tiles do you have? Are they slate?

[Phlimm]

They are tiles that look like ones you would find in a bathroom.