Fiberglass pools come in any size and shape. Pools can be heated to extend the swimming season and can be installed with fiber optic lights for night swimming. They are molded pools that are installed in your yard in one piece. Fiberglass is a strong, lightweight material that is constructed by weaving small glass threads into fabric and hardening the fabric with a special polyester resin. Adding weather-resistant gel makes a smooth finish. Because they are so smooth, fiberglass pools are more resistant to algae formation and maintain more stable pH levels.