Cold plunge maintenance schedule

A cold plunge stays clean on a cadence, not on a bottle of chemicals. The schedule below is the minimum that works for a 70–110 gallon tub with a cartridge filter. Add time if the tub sits outdoors, is shared, or runs without a cover.

A maintenance schedule is a fixed list of tasks tied to fixed intervals, so the water gets tested and the filter gets cleaned before either problem shows up.

The cadence at a glance

Print the table and keep it where you dry off. The dates matter less than the sequence: filter, test, shock, clean, drain.

After every use

Rinse your body before you get in. Sweat, lotion, and sunscreen are the raw material for cloudy water, and a quick shower removes most of them before they reach the filter.

Run the pump for 30–60 minutes after you get out, then close the cover. This moves the body oils and skin cells that just entered the water through the filter instead of letting them settle on the walls. If the tub has an automatic schedule, set it to run a short cycle after the time you usually plunge.

Check the temperature before you close the lid. A tub that has drifted from 45°F to 55°F is a different water-quality problem: warmer water grows bacteria faster and needs more sanitizer.

Weekly

The weekly session is the one that prevents most problems, and it takes about 15 minutes.

• Remove the cartridge and rinse it with a hose until the pleats run clear. If the cartridge is matted or the flow is weak after cleaning, replace it.
• Test sanitizer and pH. Adjust pH first, then sanitizer, and let the pump mix for 20 minutes before testing again.
• Shock the water after heavy use or once a week as a baseline. Run the pump while it circulates.
• Wipe the waterline with a soft cloth or brush. The ring at the waterline is biofilm, not scum, and it will seed the rest of the tub if you leave it.
• Skim leaves and hair off the surface before they sink and dissolve.

If the water is cloudy, test daily until it clears. Cloudy water means the filter and sanitizer are losing, and it is not a cosmetic issue.

Monthly

Once a month, look at the parts you cannot see from the water side.

Vacuum or brush the chiller coils. Dust on the condenser makes the compressor work harder and run longer. Check the fan for lint and the condensate drain for clogs.

Pull the pump intake screen and rinse it. Inspect the lid gasket for cracks or a flattening seal, and check every hose clamp and quick-connect for weeping. A slow drip under the tub is easy to ignore and expensive to repair once the cabinet is wet.

Test the GFCI outlet if the tub has one. Press the test button, confirm the unit shuts off, and reset it.

Quarterly

Descale the chiller with the manufacturer’s descaler if the manual calls for it. Scale on the heat exchanger reduces cooling capacity the same way dust on the coils does, and it is harder to see.

Inspect the hoses for stiffness, bulging, or cracks, and replace any hose that has lost its shape. Clean the filter housing with a soft brush, not a solvent. Check the drain valve for a slow leak, and confirm the tub still sits level.

Quarterly is also a good time to review your sanitizer doses. If you are adding more than the label suggests to hold a residual, the water change is overdue.

Seasonal

Twice a year, do the longer work: drain, deep clean, and either restart or winterize.

For a restart, drain the tub, wipe the walls and floor with a mild cleaner, rinse thoroughly, clean the filter housing, install a fresh cartridge, and refill. Run the pump and check for leaks before you add sanitizer.

For winter, drain the tub, chiller, pump, and hoses if the tub will sit below freezing. A chiller full of water can crack its exchanger. Store an inflatable dry and out of the sun; trapped moisture and UV are what kill them.

Water change interval and the log

Change the water every two to four weeks for a simple tub with a cartridge filter. With ozone or UV, light use, and consistent sanitizer, six to eight weeks is possible. The calendar is a fallback, not the rule: change sooner after a party, an illness, or a stretch of hot weather.

Keep a one-line log on the lid or in a note on your phone: date, pH, sanitizer reading, filter cleaning, water change. When the water goes cloudy, the log tells you whether you missed a week or the sanitizer system failed.

The full water-chemistry routine is in cold plunge water care. If you are choosing a filter or sizing a pump, cold plunge filtration covers the hardware side, and cold plunge chiller sizing explains why a dirty chiller behaves like an undersized one.

The short version

Filter after every use, test twice a week, clean the cartridge and shock weekly, clean the coils monthly, descale quarterly, and change the water every two to four weeks. Ten minutes a week and one longer session a month keeps a small tub out of the green-water cycle.