Testing frequency should match the rate at which each parameter changes. Free chlorine and pH change rapidly; hardness and CYA change slowly.
Recommended Testing Frequency
| Parameter | Residential Pool | Vacation Rental Pool | Hot Tub | Trigger for Extra Testing |
|---|---|---|---|---|
| Free Chlorine | Twice weekly | At every turnover | Before every soak | After heavy use, storm, hot weather |
| Combined Chlorine | Weekly | At every turnover | Before every soak | After heavy use; if odour present |
| pH | Twice weekly | At every turnover | Before every soak | After any chemical addition |
| Total Alkalinity | Monthly (or when stable) | Weekly | Weekly | After pH instability |
| Calcium Hardness | Monthly | Monthly | Monthly | After significant refill |
| CYA | Monthly (season start + monthly) | Monthly | N/A for covered spas | When using stabilised tablets |
| Salt | Monthly (salt pools) | Monthly | N/A | After significant rainfall |
| TDS | Quarterly | Monthly | Monthly | When foam or clarity issues present |
Notes
- Test after any major storm — rainfall dilutes all parameters proportionally.
- Test immediately if water clarity changes unexpectedly.
- Test after any large chemical addition to verify the adjustment worked correctly.
Sources:
- Pool & Hot Tub Alliance — Pool & Spa Operator Handbook, 2022