Fiberglass pool
Also called: fiberglass shell, gelcoat pool.
A fiberglass pool is a one-piece shell molded in a factory, delivered whole, craned into a prepared hole and backfilled. Its smooth, non-porous gelcoat surface resists algae and needs roughly 25–50% fewer chemicals than concrete, but the shape is limited to factory molds.
Why it matters
Fiberglass installs fastest and needs the least upkeep of the three in-ground types, because the gelcoat is inert and does not leach, so pH stays more stable. A shell realistically lasts about 25–30 years, and sellers' "50+" is optimistic. Over decades the gelcoat can blister, fade and craze, and a gelcoat refinish lands somewhere in the 15–25-year window. In Florida, never fully drain one without a pro managing the groundwater: the high water table can pop an empty shell out of the ground, so it needs a working hydrostatic relief valve. It is the best match for a salt pool.
In numbers
Because the shell arrives on a truck, it is limited to about 16 feet maximum width and about 8 feet deep, in fixed factory designs.