Hot tub filters do more work per gallon than pool filters. A 400-gallon hot tub filters its entire volume multiple times an hour. Body oils, lotions, sweat, and dead skin from bathers load the filter fast. A clogged filter means slower flow, weaker sanitization, more strain on the pump, and water that just won't stay clear. The schedule below is a sustainable middle for typical home use. Adjust shorter for heavy bather load or rentals.

Quick schedule

  • Every 1 to 2 weeks: rinse the filter with a garden hose.
  • Monthly: chemical-soak the filter in filter cleaner.
  • Every 3 to 4 months: deep clean with a more intensive cleaner; coincide with water change.
  • Every 12 to 18 months: replace the filter cartridge.
  • After heavy use: rinse same day.
  • After a party or many bathers: rinse plus chemical soak.

The three cleaning levels

Rinse (weekly to bi-weekly)

  1. Turn off the hot tub at the disconnect or the spa-side controls.
  2. Remove the filter (lift out from the filter well or skimmer area).
  3. Spray with a garden hose nozzle at moderate pressure. Work between every pleat from the top down.
  4. Don't use a pressure washer; it tears the filter media.
  5. Reinstall and restart the tub.

Time: 5 minutes. Catches body oils and surface debris before they bond to the pleats.

Chemical soak (monthly)

  1. Remove the filter as above.
  2. Mix filter cleaner in a 5-gallon bucket per the product label. Use spa-specific filter cleaner; don't use dish soap or household cleaners (residues foam the tub).
  3. Submerge the filter fully for the time listed on the cleaner (usually overnight, 8 to 24 hours).
  4. Rinse thoroughly with a hose. Run water until no foam comes out of the pleats.
  5. Let dry briefly (not required, but helps), reinstall, restart.

Time: 15 minutes hands-on, plus soak. Keep a second filter on hand so you can swap in a clean one while the first soaks.

Deep clean (every 3 to 4 months)

Coincide with water change. Use a stronger filter chemical (often muriatic acid based at low concentration) to dissolve mineral scale and biofilm. Always follow the product safety instructions. Always wear gloves. Always work outside or in a ventilated space.

After the deep clean, rinse extensively to remove all chemical residue before reinstalling.

What changes the schedule

  • Number of bathers and how often: 2 people once a week is different from 4 people three times a week.
  • Lotions, sunscreens, hair products on bathers: load the filter faster. Rinse off in the shower before getting in.
  • Pets: dander loads filters fast. Some hot tub manufacturers warn against pets in spas.
  • Water source: hard water leaves scale on the filter. Some sources have higher mineral content.
  • Ozonator or UV sanitizer: reduces organic load on the filter slightly; doesn't replace the schedule.
  • Hot tub use during cold weather: more debris (leaves, pollen, dust) collects when the cover is opened in windy conditions.

Signs the filter needs attention now

  • Flow from the jets feels weaker than usual.
  • Water cloudy or foamy despite balanced chemistry.
  • Filter pressure gauge shows higher pressure than the clean baseline (5 to 10 psi above clean is the rinse signal; 10+ psi above clean is the deep-clean signal).
  • Pump runs longer or cycles more often.
  • Heater struggles to reach setpoint.
  • Sanitizer demand suddenly higher.
  • Visible debris caught in the pleats.

When to replace the filter

  • Pleats start to fray, separate from the end caps, or look misshapen.
  • Chemical cleaning no longer restores flow.
  • End caps are cracked or the center core is visible.
  • Persistent dark staining on the pleats that doesn't come out.
  • Most cartridges last 12 to 18 months of normal use. Some last 2+ years; some need replacement at 9 months. Track the install date.

What to buy

  • Always replace with the exact part number the manufacturer specifies. Filters look similar but vary by micron rating and surface area.
  • OEM filters cost more but consistently match spec.
  • Aftermarket filters from reputable spa suppliers are usually fine. Avoid generic "fits all" cartridges.
  • Keep a backup on hand. A filter that needs replacement on a Friday night isn't sourcing from the spa store before Monday.

Common mistakes

  • Pressure-washing the filter. Tears the media. Hose nozzle only.
  • Using dish soap or household cleaner. Foams the tub for weeks.
  • Skipping the chemical soak. Rinsing alone doesn't remove the oils bonded to the pleats.
  • Reinstalling a soaking-wet filter without rinsing residue out. Tub will foam.
  • Running the tub with no filter to "save time." Pump damage and unfiltered water within minutes.
  • Buying a filter that's "close enough." Micron rating and surface area matter.

Good maintenance rhythm

  • Every 1 to 2 weeks: rinse the filter with a garden hose.
  • Monthly: overnight chemical soak in spa filter cleaner.
  • Every 3 to 4 months: deep clean with stronger cleaner; coincide with water change.
  • Every 12 to 18 months: replace the cartridge per the spa's part number.
  • Before any party: rinse same day, plan to rinse again after.
  • After unusual events (heavy storm with cover off, accidental contamination): rinse plus soak.
  • Keep a backup filter on hand at all times.
Add reminders to the Dome mobile app to always stay ahead of your home maintenance.

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