A hot tub is a small, hot, intensely-used pool. The combination of high temperature (typically 38 degrees C), small water volume (1000 to 2000 liters), high bather load per liter, and the closed cover environment makes hot tub chemistry roughly 10 times more demanding than a swimming pool of the same age. A hot tub that is properly maintained provides clean, safe, comfortable soaks for years. A hot tub that is neglected for even a few weeks turns into a biofilm reservoir that smells, irritates skin, and requires a full drain and disinfection to recover.
This guide walks through the daily, weekly, monthly, and quarterly maintenance tasks that keep a residential hot tub in good condition. The total time investment is about 15 minutes per week plus a 2 hour quarterly drain and refill. The cost in chemicals and filters runs 300 to 600 dollars per year for a typical setup.
Daily tasks (2 minutes)
Before each use, take a quick look and feel at the water:
Check the water level. It should be within 5 cm of the lower edge of the headrests. Top off with fresh water from the garden hose if low. Skipping this allows the pump to start sucking air, which damages the pump seals over time.
Check the temperature. The set point should be 37 to 40 degrees C. A drop of more than 2 degrees C from the set point during heat-up usually means the heater is struggling or the filter is clogged.
Pull the cover and sniff. Fresh hot tub water should smell faintly chemical (chlorine or bromine) without any sourness or muskiness. A musty smell means bacterial growth and sanitizer dose is needed immediately.
Test sanitizer if more than 24 hours has passed since the last test. Add bromine or chlorine to reach 4 to 6 ppm before getting in. Wait 15 minutes after dosing before entering the water.
Weekly tasks (15 minutes)
Once per week, run through a fuller chemistry check:
Test sanitizer, pH, total alkalinity, and calcium hardness with a 6-way test strip. Target ranges:
- Bromine: 4 to 6 ppm
- Chlorine: 3 to 5 ppm
- pH: 7.4 to 7.6
- Total alkalinity: 80 to 120 ppm
- Calcium hardness: 150 to 250 ppm
Adjust in this order: alkalinity first, then pH, then sanitizer, then calcium. Adjusting pH before alkalinity often produces unstable pH that drifts within hours.
Shock the water weekly with a non-chlorine shock (potassium monopersulfate, sold as MPS) or with a chlorine shock if the hot tub uses chlorine sanitizer. Shock burns out organic contaminants (sweat, body oils, lotions) that accumulate during the week and overwhelm the regular sanitizer dose. Dose per the product label, typically 30 to 60 grams for a 1500 liter tub. Run the jets for 15 minutes after shocking and leave the cover off for an hour.
Rinse the filter cartridge under a hose. Remove the filter from its housing, spray each pleat with a garden hose nozzle to dislodge debris, and reinstall. This 5 minute task prevents the filter from clogging and reduces the load on the pump.
Wipe down the waterline. Body oils, sunscreen, and skin cells accumulate at the waterline and form a sticky ring within a week. A non-foaming spa surface cleaner and a soft cloth removes the ring before it stains the acrylic.
Check that the cover lifter is working and the cover seals around the edges. A cover that does not seal properly loses heat (raising the electricity bill by 20 to 40 percent) and lets debris into the water.
Monthly tasks (30 minutes)
Once per month, do the deeper maintenance work:
Soak the filter cartridge in a degreasing filter cleaner overnight. Remove the filter, place it in a bucket of warm water with the cleaner, and leave it for 8 to 12 hours. Rinse thoroughly and air dry for 24 hours before reinstalling. This dissolves the body oils and lotions embedded deep in the pleats that a hose rinse cannot reach. Running a two-filter rotation (have two filters and alternate them weekly) makes this easier because one filter is always drying while the other is in service.
Test total dissolved solids (TDS). Use a TDS meter (15 to 30 dollars) and compare to the reading taken right after the last drain and refill. When TDS climbs more than 1500 ppm above the fresh-water baseline, the water is approaching the point where chemistry stops responding cleanly and a drain is due.
Inspect the jets. Remove each jet face (most twist off counterclockwise) and check for calcium scale, biofilm, or stuck debris. Soak removed jets in white vinegar for an hour to dissolve scale.
Check the ozonator or UV sanitizer (if equipped). The ozone generator should produce visible micro-bubbles when running. UV bulbs lose effectiveness after 12 to 18 months and need replacement.
Inspect the cover for damage. Waterlogged covers (heavier than 25 kg for a typical residential cover) have lost their insulation value and should be replaced. Tears in the vinyl skin allow water into the foam core which then sours and smells.
Quarterly tasks (2 hours, every 3 to 4 months)
The full drain and refill cycle is the most time-intensive task but it is the one that resets the water chemistry to a known clean state.
The night before, dose a flush chemical (such as Spa System Flush or Ahh-Some) into the running hot tub and let the jets run for 4 to 8 hours. Flush chemicals release biofilm from the inside of the plumbing where regular sanitizer cannot reach. The water will get foamy and discolored as biofilm releases.
In the morning, drain the hot tub fully. Most hot tubs have a drain valve at the base. Allow 30 to 60 minutes to drain. While the tub drains, vacuum any debris at the bottom.
Wipe the empty shell with a soft cloth and a non-foaming spa surface cleaner. Pay attention to the waterline and the foot well.
Rinse out any residual flush chemicals with the garden hose and drain again.
Refill with fresh water from the garden hose. A filter on the fill hose (a “pre-filter” rated for hot tubs, 30 to 60 dollars, reusable) removes metals, calcium, and chlorine from the source water and gives a cleaner starting point.
After refilling, balance the new water in this order:
- Test source water TDS and note the baseline
- Adjust total alkalinity to 80 to 120 ppm
- Adjust pH to 7.4 to 7.6
- Add stain and scale inhibitor per the label
- Add calcium hardness booster if calcium is below 150 ppm
- Heat to the target temperature (12 to 24 hours)
- Add sanitizer to reach 4 to 6 ppm bromine or 3 to 5 ppm chlorine
- Shock with MPS
- Run jets for 30 minutes
- Wait 4 hours and retest before getting in
Replace the filter cartridge every 3 to 4 drain cycles (12 to 18 months). A fresh filter at the start of a new water cycle gives the best result.
Annual deep clean
Once per year (typically at the start of the swim season or after winter), do a full inspection:
Check all the plumbing fittings for leaks or weeping.
Check the heater element. Calcium scale on the heater reduces efficiency and can cause the heater to trip out.
Service or replace the cover lifter if it is binding.
Check the GFCI breaker by pressing the test button and confirming it trips.
Replace the cover if it has lost insulation value or has cracks in the vinyl.
For more spa guidance, see our pool chemicals storage and safety guide, our sauna types guide, and the methodology page at /methodology.
Frequently asked questions
How often should a hot tub actually be drained?+
A residential hot tub should be drained, cleaned, and refilled every 3 to 4 months under normal use (2 to 4 people, 3 to 5 sessions per week). Heavy use (daily soaks, parties, large groups) shortens the interval to 6 to 10 weeks. Light use (occasional weekend use) extends it to 5 to 6 months. The signal is total dissolved solids reaching 1500 ppm above the source water reading, water that no longer feels fresh, or persistent foaming that does not respond to chemistry adjustments.
Why does my hot tub keep getting cloudy?+
Cloudy hot tub water has three common causes: low sanitizer (chlorine or bromine below 3 ppm allows bacteria and algae to grow), high calcium hardness combined with high pH (calcium precipitates as white haze above pH 7.8 and calcium hardness 250 ppm), or organic load from body oils, lotions, and sweat exceeding the filter capacity. Check sanitizer first, then pH, then calcium hardness, then run the filter for 24 hours continuously and clean it. Persistent cloudiness usually means a drain and refill is due.
Bromine or chlorine for a hot tub?+
Bromine is the standard hot tub sanitizer because it remains effective at higher temperatures (35 to 40 degrees C) where chlorine breaks down faster. Bromine also produces less odor in the closed-cover environment. Chlorine works but requires more frequent dosing and a stabilizer (cyanuric acid) to extend its life. For an outdoor hot tub used daily, bromine is the easier choice. For light use or for users sensitive to bromine, chlorine with a saltwater system is the cleanest alternative.
How often should hot tub filters be cleaned?+
Rinse the filter cartridge under a hose every 1 to 2 weeks to remove surface debris. Soak the filter in a degreasing filter cleaner overnight every 4 to 6 weeks to dissolve embedded body oils and lotions. Replace the filter cartridge every 12 to 18 months because the pleated material breaks down even with cleaning. A two-filter rotation (alternate between two cartridges every two weeks) gives each filter time to fully dry, which kills any embedded bacteria.
Do I need to test the water every day?+
For a hot tub used 3 plus times per week, test sanitizer (chlorine or bromine) and pH 3 times per week. For daily-use hot tubs, test daily before the first use. Test total alkalinity, calcium hardness, and stabilizer weekly. Test for total dissolved solids monthly. Inexpensive 6-way test strips give fast readings. A liquid drop test kit (Taylor K-2106 for bromine) gives more accurate readings for troubleshooting persistent problems.
