How often should you clean a hot tub filter?
Updated July 2026
Rinse a hot tub filter cartridge once a week, give it a chemical soak once a month, and replace it entirely every 1–2 years. Heavy use bumps the rinse to twice a week. That layered schedule exists because warm, jetted water is a perfect incubator: a gunked filter starves the pump, clouds the water, and lets bacteria and slimy biofilm take hold in exactly the conditions they love.
What changes the interval
| Your situation | Interval | Why |
|---|---|---|
| Every week | Hose rinse | Flush grit from the pleats before it packs in |
| Every month | Overnight chemical soak | Dissolves body oils, lotion, and scale |
| Heavy use or many bathers | Rinse twice a week | More bathers means more oils and debris |
| Right after a party | Rinse now | A crowd loads the filter in one sitting |
| Every 1–2 years | Replace the cartridge | Pleats break down and stop filtering |
| Foamy or cloudy despite good chemistry | Deep clean or replace | Often the filter, not the water balance |
The cost of skipping it
What skipping it costs: a clogged filter drops circulation, so the heater trips its flow switch and leaves you with a cold tub, while dead spots in the water grow bacteria and slimy biofilm. Push it further and you are draining and refilling early and fighting foam and odor with extra chemicals. A replacement cartridge is only $15–40; a new circulation pump runs $150–400.
How to do it (10 minutes weekly · overnight soak monthly)
- Turn the tub off at the breaker or panel so the pump cannot run dry while the filter is out.
- Lift out the cartridge and spray it with a hose from the top down, fanning open each pleat to flush out trapped grit.
- Once a month, soak it overnight in a bucket of water and a dedicated filter cleaner, then rinse thoroughly (never dish soap, which foams in the jets for weeks).
- Let it dry fully if you can, or drop in a spare so the tub is never run without a filter.
- Replace the cartridge every 1–2 years, or sooner if the pleats are matted flat or the end caps crack.
Knowing the interval is the easy half. OnOtto reminds you at the right interval, and it won't let you snooze it into next year. Tasks persist until they're done, and completing hot tub filter cleanings schedules the next one automatically.
Put this on autopilot, free for 30 daysFrequently asked questions
How do I chemically soak a hot tub filter?
Drop the cartridge in a bucket of water mixed with a dedicated filter cleaner (or a diluted TSP solution) and leave it overnight, then rinse it very thoroughly. Skip dish soap and laundry detergent, which foam up through the jets for weeks afterward. A monthly soak dissolves the body oils, lotions, and mineral scale that a weekly hose rinse packs deeper into the pleats rather than removing.
Should I keep a spare filter cartridge?
It is the easiest upgrade to your routine. Buy two identical cartridges and rotate them: while one soaks and dries, the other is in the tub, so the pump is never run without a filter and each cartridge dries fully between uses. Drying kills a lot of biofilm, and a rotated pair often lasts noticeably longer than a single cartridge worked continuously for the same money.
Why does a dirty filter matter so much in a hot tub?
Warm water is a perfect incubator: a clogged filter drops circulation, so sanitizer is not spread and dead spots let bacteria and biofilm bloom fast. Low flow also trips the heater flow switch, throwing an error and leaving you with a cold tub. And the cloudy, foamy water most people blame on chemistry is often just a filter that can no longer keep up with the bather load.
How often should I actually change the water?
A common rule: divide the tub gallons by ten, then by the number of daily bathers, to get the days between changes, which lands most home tubs around every 3–4 months. Diligent filter care stretches that interval by keeping the water clean, but it does not replace it: dissolved solids build up no matter how good the filter is, and eventually the water simply needs to go.