Quick take
Use a neutralizing system matched to measured pH and alkalinity. Calcite is common for milder acidity; chemical injection is often preferred when stronger correction is needed.
Why carbon does not fix acidity
Activated carbon can remove chlorine and many organics but does not reliably raise low pH.
Calcite neutralizers
Calcite media gradually dissolves and raises pH. Media consumption and added hardness must be included in maintenance planning.
Chemical feed
Soda ash or similar feed systems can correct pH without relying only on dissolving mineral media.
Test after treatment
Confirm finished-water pH and watch for ongoing corrosion indicators after installation.