The filter cartridge catches the debris that the water carries past it. When it clogs, water can’t flow through it the way it should. Cleaning it is a short job: power off, lift it out, rinse, deep-clean now and then, and put it back.
Your spa’s owner’s manual wins wherever it differs from this guide.
Why a dirty filter shows up in the water
Hot Spring’s Hot Spot owner’s manual says that if the filter isn’t cleaned, it “may clog and restrict water flow, which causes improper filtration and poor jet performance.” Master Spas’ maintenance guide says the same thing from the other side: a filter that won’t come clean can leave a lack of flow and cloudy water even when the water is chemically balanced.
If your water is cloudy, the filter is one of the things to check, after sanitizer and balance. See why is my hot tub water cloudy? If you have suds, see hot tub foam fixes.
How often: a quick rinse vs a deeper clean
Makers set different schedules, so check yours:
- Master Spas: rinse the filter fabric with a garden hose once a week, and use a filter cartridge cleaner on it once a month.
- Hot Spring (Hot Spot manual): clean the filter cartridge every four weeks, depending on how often the spa is used, and check the skimmer basket and weir at least once a week.
If your manual gives a schedule, follow it.
Step by step
- Turn the power off. Hot Spring’s first step is to disconnect the spa from the power supply. Master Spas says never to run the pumps, including the circulation pump, without the filters in place, because debris can be drawn into them.
- Clear the compartment. Hot Spring says to remove any floating items from the filter compartment before you take anything apart.
- Lift the cartridge out the way your manual shows. On the Hot Spot models, that means turning the retainer handle counterclockwise and removing the retainer, cover and cartridge. Hot Spring warns not to remove the filter standpipe or suction fittings.
- Rinse. Spray the cartridge with a garden hose. Hot Spring notes you may need to rotate it while spraying to clear debris lodged between the pleats.
- Deep-clean on schedule. For the monthly clean, soak the cartridge in a filter cleaner your manual allows, following the package directions, then rinse it again. Hot Spring describes this as removing mineral and oil buildup.
- Reinstall. Reverse the removal steps. Hot Spring says not to overtighten. Don’t run the spa without the cartridge in place.
- Power back on and retest. Check sanitizer and pH once the water is circulating again.
Master Spas suggests keeping a spare cartridge so you can swap one in while the other is cleaned and left to dry, which it says can help a cartridge last longer.
When to replace instead of clean
Master Spas names these signs:
- The pleats begin to deteriorate.
- The filter is not coming clean, so water doesn’t flow through it well and stays cloudy even when it’s chemically balanced.
- A year has passed. Master Spas says to replace the filter with a new one once a year.
Your own manual may give a different interval. Use the one for your spa.
After cleaning: check the water
A clean filter doesn’t replace water care. Test once the water has circulated:
- Sanitizer: keep free chlorine at 3 ppm or higher, or bromine at 4–8 ppm, whenever the tub is in use, with your own registered product (these are CDC’s hot tub figures).
- pH and alkalinity: see why hot tub pH keeps rising.
- Fill water: if you’re refilling at the same time, Water Match estimates whether your hose water runs Soft, Balanced or Hard. For hard fill, see start-up chemicals for hard-water hot tubs.
What to do next
- Try Water Match. Enter your ZIP to see what your fill water is like.
- Join the free founding list for the planned Cycle Box, which isn’t on sale yet.
More guides:
Check your water, then join the free founding list
Enter your ZIP to see whether your fill water is Soft, Balanced, or Hard. After your result, you can join the free founding list for Cycle Box, which isn’t on sale yet.