Monthly maintenance extends between the weekly quick checks and the quarterly water change. It catches slow-developing issues before they require expensive repairs.
Key Facts
- Monthly filter degreaser soak removes oils and mineral deposits that rinse-only cleaning cannot clear.
- Test CYA monthly if using stabilised chlorine products — it accumulates in hot tub water.
- Inspect jets and air controls monthly for scale buildup and proper function.
- Check the cabinet and equipment compartment for moisture, leaks, or pest activity.
Deep Filter Cleaning
A weekly rinse removes surface debris but does not penetrate the pleats to remove body oils and fine minerals that build up over time. Once per month, remove the filter cartridge and soak it overnight in a filter degreaser solution (sold specifically for spa filters). After soaking, rinse thoroughly with a garden hose. Inspect the cartridge for tears, collapsing pleats, or brown staining that does not wash out — these are signs the cartridge needs replacement. A clean filter is the most important piece of hot tub maintenance equipment; a fouled filter allows the water to degrade faster than any chemical adjustment can correct.
Monthly Chemistry Audit
Run a complete water test including all four core parameters plus CYA. In hot tubs, TDS should also be checked monthly — TDS above 1,500 ppm over your fill water baseline indicates the water is ready for a change. Calculate the Langelier Saturation Index at the current water temperature. In heated spas, the LSI rises with the temperature and the same chemistry that is acceptable in spring can become scaling by summer. Adjust any out-of-range parameters, documenting both the reading and the correction in your maintenance log.
Equipment and Cabinet Check
Open the equipment cabinet and inspect for moisture on electrical components (indicating a leak), scale deposits on the heater element (visible as white crust), and unusual odours from the pump area. Run the jets on each setting and verify they have consistent flow. Check the air controls (if present) to ensure they open and close freely — stuck air controls cause aeration problems that accelerate pH drift. Check the cover for deterioration: a waterlogged cover (more than 50 lbs when lifted) is a significant heat loss point and should be replaced.
Examples
First Saturday of each month: remove the spa filter cartridge. Fill a bucket with a filter degreaser solution and submerge the cartridge completely. Soak overnight (12–24 hours). Sunday morning: remove, rinse thoroughly with a hose, and inspect. Three-month-old cartridge looks clean but has one small tear in a pleat — time to order a replacement. Meanwhile, a backup cartridge (always keep one spare) is installed. Total time: 10 minutes active work, overnight soak.
Common Mistakes to Avoid
- Soaking the filter in chlorine solution instead of a dedicated filter degreaser — chlorine bleaches the cartridge but does not remove oil and mineral buildup.
- Not keeping a spare filter cartridge — monthly cleaning requires the filter to soak overnight, leaving the spa unfiltered if no backup is available.
- Ignoring TDS testing and running old water that needs replacement because it looks clear.
- Pool & Hot Tub Alliance — Pool & Spa Operator Handbook, 2022
- Taylor Technologies — Pool/Spa Water Chemistry Reference