Why would the tiles in your swimming pool be falling off?
Check your swimming pool balance. Your Calcium Hardness level may be low. Hope this helps.
You must have a cantilevered deck. This is often a cause of loose or broken tiles. I think your pool would have to be hopelessly out of balance for very long times to cause deterioration of the grout etc. But sometimes certain types of tile do come loose and have to be replaced.
Yes, you can use ordinary ceramic wall tiles (CWT) for swimming pool but it wont be as durable as the vitrified tiles (VFT). CWT were not as hard as the VFT and only inteded for residential or wall uses. The thin glazing will easily chip specially on edges and will cause injury to the users. My opinion, if your on a budget, use the vitrified floor tiles, if you want durability, use the porcelain or…