We bout a house with a pool 2nd pool in 2 years and we would like to update it a *little* the problem is we don't know if it is a liner or fiberglass walls and not sure if we can replace the plastic trim at the top with tile. 1st question how do you know if your pool has a liner or something else and 2nd question can I just rip that trim off and put tile in its place? Newbie here..