Could old pool plaster be why my water is very acidic?
I bought a house with a gunite pool about 3 years ago. I never asked when the pool was built or if it was ever re-plastered. So let's assume the pool was built in 1980 and it was never re-plastered. I have to add soda ash about every month to keep the pH above 7.2. It was 6.8 about two years ago before I started adding soda ash. With enough soda ash i have gotten the pH to 7.8, but it always turns acidic. I feel like the amount of soda ash I am using to maintain this pool is ridiculous and I'm missing the bigger picture. When I talk to other pool owners in the area, they don't seem to have acidic water. If anything their water is too basic.
I hear that plaster can last 5 - 20 years. What happens when it goes bad?