Hot tub care, from the manuals and the CDC
Short answer
Hot tub care is three habits: keep Free chlorineThe chlorine still able to kill germs. CDC says keep it at 3 ppm or more in a hot tub.In the glossary at 3 ppm or more with pHHow acidic the water is. CDC gives 7.0 to 7.8 for hot tubs. Low pH corrodes metal; high pH clouds the water and slows chlorine down.In the glossary 7.0 to 7.8 (CDC), clean the filter about once a month, and change the water every few months. The six makers' manuals we read give 1 to 6 months.
Keep the water at these levels
- Test and adjust the water several times a week, a few minutes each time: see hot tub water chemistry.
- Clean the filter about once a month: how to clean a hot tub filter.
- Drain and refill every 3 to 4 months for most owners: how to drain and refill.
What does hot tub care involve?
A hot tub is a few hundred gallons of water held near body temperature, with several people in it at once. That is ideal for germs and hard on chemistry: sanitizer gets used up fast, sweat and soap pile up, and evaporation leaves minerals behind. Care is the routine that keeps ahead of it. Sanitizer kills germs, the filter catches what floats, balance keeps the water from eating or scaling the tub, and a periodic water change resets everything the chemicals can't remove.
Water chemistry
- Hot tub water chemistryCDC: free chlorine 3 ppm or more, bromine 4 to 8 ppm, pH 7.0 to 7.8. Alkalinity and calcium targets from five makers' manuals, side by side.
- Hot tub pHHot tub pH belongs between 7.2 and 7.8 (CDC allows 7.0 to 7.8). What high and low pH do, why alkalinity comes first, and how to raise or lower it.
- Hot tub alkalinityHot tub total alkalinity targets run 40 to 150 ppm across five makers' manuals, most often 80 to 120 or 100 to 150. Why you fix it before pH.
- Hot tub chlorine levelsCDC says at least 3 ppm free chlorine in a hot tub and 4 to 8 ppm bromine; makers aim for 2 to 5. Free vs total chlorine, and what to do when it's high.
- Chlorine vs bromineChlorine at 3 ppm or bromine at 4 to 8 ppm (CDC). How they differ, which makers allow bromine, and why Master Spas bars it with ozone or UV.
- How to shock a hot tubShock burns off spent chlorine and body waste. Hot Spring's manual gives 1.5 tsp dichlor per 250 gallons, weekly or monthly. Chlorine vs non-chlorine.
- Calcium hardness and hard waterMaker targets for hot tub calcium hardness run 75 to 150 ppm (Hot Spring) to 180 to 250 ppm (Master Spas). Scale, foam, and what to do about hard water.
- Hot tub stains and metalsClear green, brown or orange hot tub water and shell stains usually mean iron, copper or manganese. The makers' fixes: a sequestrant and a pre-filter.
- Test strips vs test kitsCDC rates test strips less accurate than a DPD drop kit. When strips are enough, how to read them, and what to test 3 times a week (Master Spas).
- Hot tub chemicals you needThe 5 hot tub chemicals every owner needs, the extras makers add, and what never to use: pool chemicals, trichlor, muriatic acid. Product types only.
Water problems
- Cloudy hot tub waterCloudy hot tub water has 6 usual causes, from a dirty filter and low sanitizer to old water. The makers' fixes, in the order to try them.
- Hot tub foamHot tub foam is soap and oils whipped up by the jets. Defoamer is a stopgap; Hot Spring says the water lasts about 4 months before soap wins.
- Green hot tub waterCloudy green hot tub water means algae and low sanitizer; clear green means copper or iron. The 2 fixes from Master Spas' and Hot Spring's manuals.
- Hot tub smellsA chlorine smell means spent chlorine, not too much; musty means bacteria or algae. CDC calls a strong chemical smell a problem. 4 smells and fixes.
Changing the water
- How often to change hot tub waterMakers say every 1 to 6 months, most often 3 to 4. CDC's formula (gallons / 3 / daily bathers) gives 58 days for a 345-gallon tub used by two a day.
- How to drain and refill a hot tubDrain a hot tub in 5 steps: power off at the breaker, hose on the drain valve, open it, clean, refill via a pre-filter. Hot Spring: no refill below 50°F.
- Biofilm and line flushingBiofilm is slime that clings to hot tub pipes, where sanitizer can't reach. Master Spas says flush before draining; CDC says scrub surfaces at every drain.
- Hot tub start-upStart up a hot tub in 7 steps: fill via a pre-filter, add a sequestrant, balance alkalinity, pH and calcium, then add sanitizer last (Master Spas).
Filters, cover and cleaning
- How to clean a hot tub filterClean a hot tub filter monthly: power off, hose each pleat top to bottom, soak in filter cleaner. Bullfrog says every 3 to 6 weeks, and no brushes.
- When to replace a hot tub filterReplace a standard hot tub filter about every 12 months (Master Spas) or 18 (Sundance); fine inserts every 6. How to tell a cartridge is worn out.
- Hot tub gallons and filter size by modelGallons for 363 hot tub models and filter area for 227, from makers' spec sheets: median 345 gallons and 50 sq ft. Chemical labels dose by gallons.
- Hot tub cover careClean a hot tub cover monthly with mild soap and water, rinse the underside with water only, and leave it open 15 to 20 minutes after adding chemicals.
- How to clean a hot tubClean the shell with a soft cloth and spa cleaner at each drain, wipe the scum line as it forms, and soak stiff jets in white vinegar (Master Spas).
Settings, seasons and routine
- Hot tub temperatureNo hotter than 104°F, per CPSC and CDC. Master Spas calls 100 to 104°F safe for a healthy adult. Children, time away, and checking the display.
- Hot tub vacation modeAway 5 to 14 days? Hot Spring says set the lowest temperature, about 80°F, and shock before and after. Bullfrog's Vacation mode drops 20°F.
- Winterizing a hot tubMaster Spas doesn't recommend winterizing, and Jacuzzi tubs guard against freezing while running. If you shut down, 2 makers say have a dealer do it.
- Hot tub maintenance scheduleA hot tub schedule from 6 owner's manuals: test 3 times a week, clean filters monthly, change water every 3 to 4 months, service UV and ozone yearly.
Troubleshooting
- Hot tub not heatingHot tub not heating? Check 6 things: set point, economy mode, cover, filter, water level, air lock. Then reset power for 30 seconds or call a technician.
- Weak hot tub jetsWeak hot tub jets mean low water, a clogged filter, closed jets or valves, or an air lock after a refill. 7 owner checks before calling a technician.
- Hot tub tripping the GFCIA hot tub GFCI trips when current leaks where it shouldn't. Reset it once; if it trips again, call a technician. How to run the monthly 30-second test.
What can an owner fix, and when do you call a technician?
An owner can check the breaker and reset the GFCI once, clean or swap the filter, top up the water, open closed jets and valves, and fix the chemistry. Most no-heat and weak-jet calls end there; Hot Spring's and Jacuzzi's troubleshooting tables start with exactly those checks. A code on the topside panel points to the part; see hot tub error codes.
Where the owner's part ends
Anything behind the equipment panel: turn off power at the breaker and call a technician.
Heaters, pumps, control boards and wiring run on mains voltage next to water. Never bypass a sensor, a high-limit switch or the GFCI to get a tub running.
How hot should a hot tub be?
No hotter than 104°F, the limit CPSC and CDC both give. More on settings, children and pregnancy in hot tub temperature.
The details
What each maker's manual says, how often each says to change the water, and how we wrote these guides.
What CDC and each maker's manual say
7 sources
| Free chlorine | pH | Total alkalinity | Bromine | Calcium hardness | |
|---|---|---|---|---|---|
| CDCAdvice for hot tub users | 3 ppm or more | 7.0 to 7.8 | Not given | 4 to 8 ppm | Not given |
| CDC Legionella toolkitWritten for public and display hot tubs | 3 to 10 ppm | 7.2 to 7.8 | Not given | 4 to 8 ppm | Not given |
| BullfrogX Series manual, 2026 | 3.0 to 5.0 ppm | 7.2 to 7.6 | 80 to 120 ppm | 3.0 to 6.0 ppm | 150 to 250 ppm |
| Hot SpringHighlife manual, 2026 | 3 to 5 ppm (1 to 5 acceptable) | 7.2 to 7.8 | 40 to 120 ppm | Granular only; no range given | 75 to 150 ppm |
| JacuzziJ-300 manual, 2025; chlorine figure is for its cartridge system | 0.5 to 1.0 ppm | 7.4 to 7.6 | 100 to 150 ppm | Not given | 150 to 250 ppm |
| Master SpasTwilight manual, 2026 | 2 to 4 ppm | 7.2 to 7.6 | 80 to 150 ppm | 3 to 5 ppm | 180 to 250 ppm |
| Sundance880 manual, 2025; without its UV system running | 3.0 to 4.0 ppm | 7.4 to 7.6 | 100 to 150 ppm | 2.0 to 4.0 ppm | 150 to 250 ppm |
How often each maker says to change the water and clean the filter
6 makers
| Maker | Change the water | Clean the filter |
|---|---|---|
| Bullfrog X Series | Every 1 to 4 months | Every 3 to 6 weeks |
| Caldera | Every 3 to 4 months | Monthly |
| Hot Spring | Every 3 to 4 months (up to 12 with its salt system) | Monthly |
| Jacuzzi | Every 3 months | Monthly |
| Master Spas | At least every 180 days | At least monthly |
| Sundance | Every 3 to 6 months | Monthly |
How we wrote these guides
Every figure on these pages comes from CDC, CPSC, EPA or a maker's current owner's manual, named next to it. Where the makers disagree, we show each one. The median tub in our data holds 345 gallons, from 363 spec sheets; chemical labels dose by gallons, so look up your tub's gallons and filter size.
Care guides
30
Maker manuals read
6
Common questions
How much maintenance does a hot tub need?
A few minutes several times a week to test and adjust the water, a filter cleaning about once a month, and a drain and refill every 3 to 4 months for most owners, per the makers' manuals.
What are the right chemical levels for a hot tub?
CDC says free chlorine at 3 ppm or more, or bromine at 4 to 8 ppm, and pH between 7.0 and 7.8. Makers add total alkalinity and calcium hardness ranges in their manuals.
When should I call a technician for my hot tub?
When the fix is behind the equipment panel: heaters, pumps, control boards or wiring, or a GFCI that trips again after one reset. Turn off power at the breaker first.
Sources
10
- CDC: What you can do to stay healthy in hot tubsChlorine at least 3 ppm, bromine 4 to 8 ppm, pH 7.0 to 7.8, water no hotter than 104°F
- CDC: Controlling Legionella in hot tubsControl limits, the water replacement formula, scrubbing and filter care (written for public hot tubs)
- CPSC: warning for pools, spas and hot tubs (1996)Keep spa water at 104°F or below; use a locked safety cover
- EPA: use of the term "shock" in pool and spa products"Shock" is a pesticide claim; oxidizer-only products must not claim to sanitize
- Bullfrog X Series owner's manual, 2026
- Caldera Paradise Series owner's manual, 2026
- Hot Spring Highlife Collection owner's manual, 2026
- Jacuzzi J-300 Collection owner's manual, 2025 (Rev E)
- Master Spas Twilight Series owner's manual, 2026
- Sundance 880 Series owner's manual, 2025 (Rev E)
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