One of the chief complaints about fiberglass pools are spider cracks, also called hairline cracks. These can appear in the gel coating of a fiberglass pool and are caused by pressure in certain areas of the outer shell of the pool. This pressure most often occurs during installation. While spider cracks do not cause structural damage to the pool, they are unattractive and attempts to repair them might appear very obvious and look worse than the cracks themselves. While most fiberglass pool manufacturers give lifetime guarantees on their product, none guarantees their pools against spider cracks forming in the gel coat.
No longer confined to marine blue or white gel coats, fiberglass pools are now available in a choice of beautiful colors. Unfortunately, many of these colors are difficult to match when it comes to materials needed to make repairs. Attempts to repair the pool are often quite conspicuous. Fading finishes are also a common problem with colored fiberglass pools, the result of the gel coat being exposed to the sun for long periods of time. Most fiberglass pools also develop stain, and while minor ones can be easily dealt with, large black ones caused by cobalt bleeding can only be corrected by refinishing the entire pool.
Sand that has been saturated with water is often used as backfill material around fiberglass pools, and the plumbing is encased within it. Compacting the sand can be difficult, and when it settles after installation, it sometimes impacts the plumbing by forcing downward pressure on it, resulting in leaks. This problem can be avoided if the installer uses gravel as the backfill, which provides a stable environment for the plumbing.
Again, saturated sand backfill is the culprit. While many fiberglass pools with this type of backfill have no problems, some develop a bulge in the pool wall due to the sand liquefying against the fiberglass, which is very flexible. Liquefied sand is heavier than the water inside of the pool, causing bulges to form in the wall if it is not strong enough to hold its shape. Because fiberglass pools are also light and intended to hold water year-round, structural damage can occur if the ground pressure is not well regulated.
The problems with fiberglass pools can often be avoided and corrected, but it is important to contract with knowledgeable pool dealers who only work with quality installers and reputable manufacturers.