Good morning. We used a solid slab of granite 4 inches thick with a bush hammer finish for nonslip That was submerged a quarter inch below water. Attached lighting to the underside of the slab to shine down onto the floor to give the back light glow. Worked perfectly!

Thank you for the info. It is very helpful. Was this a more shallow space?

Who sells these granite bush hammer steps? The submerged steps are a beautiful design.