High pH
Pool water pH above 7.8, reducing chlorine effectiveness and promoting scale formation.
Definition
High pH (above 7.8) significantly reduces free chlorine effectiveness — at pH 8.0, only 22% of FC is in the active HOCl form (compared to 67% at pH 7.2). High pH also promotes scaling (high positive LSI), causes eye irritation through a different mechanism than low pH, and can cause white cloudiness from calcium carbonate precipitation. High pH commonly results from adding too much soda ash, sodium bicarbonate increasing pH as a side effect, CO₂ off-gassing from aeration (waterfalls, jets), and some source water. Treatment involves adding muriatic acid (hydrochloric acid) or dry acid (sodium bisulfate).
Quick Facts
- Ideal Range
- N/A (pH should be 7.2–7.6)
- Units
- pH units
Relationships
Outgoing Relationships
- related to → Scaling
Incoming Relationships
- causes ← pH
- causes ← Scaling
- solves ← Muriatic Acid