I have a two year old 21K gal blue fiber glass. I have had to re gel coat serveral times due to waxing. ( Manuf. issue). so now we have the bottom correct and its looks great. I have noticed small lighting bolt hair line cracks ..with water on it, you dont notice. It starts on the swallow end almost on the wall and runs down. I would rather not touch it or possible a clear appoxy for safey. Can anyone give me advice if this will get worst. The pool installer says leave it. Phillip Fiber glass two years old