Armour Glaze gives an additional 5 year warranty over and above
the mandatory two years - a total of 7 years - without any specific
pool chemical balance required.

The Office of Fair Trading requires a two (2) year warranty on pool surfaces. They are considered a decorative finish, not structural which requires a longer warranty.
After the two year period owners rely on the integrity of the renovation company to come back for any repairs. After two years legal steps may be the only recourse. Proof that the pool has been maintained with a specific chemical balance throughout its life may be required.
Unlike cement based pools which require tight chemical balancing, fibreglass is classed as an inert surface and therefore the chemical balancing is much simpler and more cost effective.
We only require that you keep the pool filled and in a swimmable condition - nominal ph levels, chlorine levels etc  are required.

Swimming Pool Repairs & Renovations