Fibre Tech is a fiberglass resurfacing process. As such, the gel coat surface is susceptible to damage from the concrete in the pool.
If it were my pool, I would empty it, power-wash and refill. However, there is a warning on the manufacturers website stating:
if the pool is drained without first relieving the hydrostatic pressure on the pool shell, the pool shell can buckle and crack. All damage to the pool shell resulting from draining the pool without professional assistance of your authorized Independent Fibre-Tech dealer is the owner’s responsibility
Why not ask your local dealer for advice, or contact the manufacturer directly. See the
Fibre Tech website.