Water Replacement
Partially or completely draining and refilling pool or spa water to reduce dissolved compound levels.
Definition
Water replacement (partial or full drain and refill) is the only way to reduce CYA, calcium hardness, TDS, and salt when they exceed maximum levels. A partial drain replaces a percentage of the water — a 50% drain reduces all dissolved compounds by 50%. Hot tubs require complete water changes every 3–4 months due to high bather-to-water ratios that accelerate TDS and combined chlorine accumulation. Pool partial drains are typically 25–50% and are triggered by CYA above 80 ppm, calcium above 500 ppm, or TDS above 3,000 ppm.
The source below directly supports the 1,500 ppm TDS-increase-over-baseline trigger (hot tubs) and the general principle that high CYA/TDS should be managed by water replacement. It does not itself state the specific CYA (80 ppm), calcium hardness (500 ppm), or pool TDS (3,000 ppm) figures above -- those remain common industry guidance without an independently confirmed primary source.
Sources
- Water Conservation During Droughts (PHTA Fact Sheet) — Pool & Hot Tub Alliance (PHTA), Recreational Water Quality Committee (Industry standard (ANSI-accredited))
Relationships
Outgoing Relationships
- solves → Low Chlorine
- related to → Cyanuric Acid
- related to → Total Dissolved Solids
Incoming Relationships
- affected by ← Cyanuric Acid