Is $6,000 to replaster a pool with white plaster a fair price?

I recently bought a house with an existing 16x17 inground cement pool (~6500 gallons). I am already having the tile and coping redone. When I bought the house in early March, the pool was a green mess, though it seems to be in overall working condition with no leaks. I mistakenly pumped out the water and refilled it, but saw no signs of chips or chunks of old plaster. The entire inside of the pool is now uniformly gray and rough like a pumice stone, unlike previous real estate listings from 2019 which showed a blue water color. The previous owner claimed the pool was still blue last fall. I'm wondering if chemicals could have caused the plaster to completely disappear. I'm also curious if there's a significant price difference between white and blue plaster.