Steel Schedules in any vessel should be determined by a structural engineer. Swimming pools will hold Tons of water, they need to be strong or you will pay everyday for that pool to loose water.
Why, its simple a structural engineer knows what schedule should be used in a pool.
Ask your pool builder if they regularly work with an engineer concerning soils testing to ensure your swimming pool will have the proper steel to concrete ratio. How do they do this, by working with a Structural Engineer.
If they do not, or they cannot show you plans designed for specific projects , I suggest you look for a more qualified pool builder, who by the way is most likely going to be more expensive, since He/She decided to do it right.
Crystal Pools LLC uses structural engineers and soils testing to ensure that we properly place the steel and concrete ration in your swimming pool.
Photo: This project is under way the pool is slightly above grade which will require a double cage wall and additional wall thickeness.