I have a ten metre by five metre swimming pool which is about one and a half metres deep.  It is about twenty five years old and the glaze has gone off the tiles.  This means that in summer the algae sticks and it is all difficult to clean.
I need to tile it but would appreciate anybodies experience of doing a similar project.  What I really need to know are :-
Which are the best tiles and where is the best place to buy them ?
Do I have to take the old tiles off or can I just tile over them, I have heard of this for floors and walls but I am not sure if it would work in a pool ?
I am thinking about using the little glass tiles. I have been told that when you put these on you can use the initial glue as grouting as well so you just pat them down untill the glue comes through the web and then just smooth them over and its done.
What sort of cement/glue is needed ?
Has any one tiled a swimming pool just using ordinary tiles and know any reasons why you cannot.

All suggestions gratefully accepted.

Have you considered a pool liner?
Depends on you circumstances/long term plans etc.
I know a lad in the UK that does exactly what you propose to do but basically sticks a liner with a mosaic pattern on inside the roughest of pools....in the UK they guarantee them for ten years.... not sure about Spanish sun/UV levels though.... just a thought