How to clean a hot tub filter
Quick answer
Rinse the cartridge under a hose every week or two, soak it in a filter cleaner overnight every month to strip oils and scale a rinse leaves behind, and replace it every 12 to 24 months when the pleats go soft or stay gray. A clogged filter is the most common reason for cloudy water.
The filter is doing quiet, constant work, and almost every clarity problem traces back to it. The routine is easy once it is a habit.
The routine
- Weekly rinse. Turn off the tub, remove the cartridge, and hose it out, spreading each pleat to flush trapped grime. Skip a pressure washer; it tears the fibers.
- Monthly soak. Soak the cartridge in a spa filter cleaner overnight to dissolve body oils and scale that water cannot rinse away, then rinse and refit. Keeping a spare lets you swap and soak without downtime.
- Replace yearly-ish. Cartridges wear out. When the pleats no longer stand up, the material stays gray after cleaning, or the ends are cracked, fit a new one. Look up your model's part number.
Signs the cartridge is done
A cleaning brings most filters back, but no cartridge lasts forever. Replace it when you see any of these:
- The pleats have gone soft and lie flat instead of standing up.
- The fabric stays gray or stained after a proper soak; it is not catching anymore.
- The end caps are cracked or the center core is split, which lets water bypass the media.
- The water clouds within a day of a fresh clean, with the chemistry in range.
- It has simply been a year or two of regular use. Most spa cartridges last about 12 to 24 months.
To find the right replacement, read the part number molded into the cartridge end cap, then look it up in our filter cross-reference to see the Pleatco, Unicel, and Filbur equivalents that fit.
What helps
A dedicated filter cleaner for the monthly soak, and a spare cartridge so the tub is never down.
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Common questions
Can I clean a cartridge in the dishwasher or with bleach?
No. Dishwasher detergent and bleach damage the fibers and leave residue that foams the water. Use a rinse plus a spa filter cleaner soak, which are made for the job.
How long should a soak be?
Overnight, around 8 to 12 hours, in a bucket of water dosed with filter cleaner. Rinse thoroughly afterward so no cleaner carries into the tub, which would cause foam.
Why does a clean filter matter so much?
It is the only thing physically removing particles from the water. A clogged cartridge stops pulling debris out, so the water clouds and the pump strains. Most cloudy-water calls are really dirty-filter calls.