The Benefits of Waterline Tiles
Why We Install Waterline Tiles
Most swimming pools are fitted with waterline tiles to manage the insoluble, floating veneer of pollen, sunscreen, and body oils that forms the scum line at the air/water interface. The bath tub ring formed is usually evidenced as a yellowy, brown stain that can be locked into place with a thin film of translucent inorganic calcium scale deposits.
How Waterline Tiles Stop “The Ring”
Tiles inhibit the formation of this “ring” through the hard impermeable glaze that coats them; forming a barrier to which debris can’t easily mechanically fix itself to; also the baked, glazed coating is chemically inert and won’t chemically bond to any floating compounds.
Pools that have been fitted with a cementitious lining are very chemically reactive and porous in structure, meaning debris and other harmful compounds can find many points to adhere themselves to.
In your position I would probably fit the proposed travertine pavers as a large format waterline tile (hopefully they can supply 10mm or so thick tiles made from the same material (in addition, please check that the material is suitable for water immersion).