Here is how to clean hot tub filters in short: turn the power off, lift out the skimmer basket and cartridge, hose the pleats from the top down, soak the cartridge in a spa filter cleaner for as long as the product label says, rinse it again, and put it back before you restore power. A spare cartridge lets one soak and dry while the other works. Steps below follow the Caldera Spas Paradise Series owner’s manual and other maker guides; your own manual has the final word.
How often to clean and when to replace on a schedule is already covered in our hot tub maintenance guide (American Spas, for example, says rinse weekly, deep clean monthly and replace about once a year). This guide is about the cleaning itself, what to avoid, and how to tell a worn cartridge from a dirty one.
How to clean hot tub filters step by step
This is Caldera’s procedure with practical notes added.
- Turn off power to the spa. Use the shutoff your manual names (often the breaker or GFCI). Caldera warns not to remove the weir, basket or filter while the spa is running.
- Remove the skimmer basket and weir. On Caldera Paradise models you push the basket down slightly and turn it counterclockwise to unlock it. Other brands twist or lift out; check your manual.
- Lift the cartridge straight out.
- Rinse. Use a garden hose with a straight or fan nozzle. Unicel’s care page says to work from the top down with the nozzle at about a 45 degree angle, aiming between the pleats. Caldera adds that rotating the filter while spraying helps clear debris lodged between pleats.
- Soak in a filter cleaner. Caldera says to always use a filter degreaser to remove mineral and oil buildup, soaking the cartridge according to the package directions. Master Spas describes traditional cleaners as an overnight soak.
- Rinse again, thoroughly. Master Spas stresses removing all cleaner residue, since leftovers can affect water quality.
- Dry, or swap in the spare. A fully dried cartridge also shows damage more clearly. Master Spas suggests a second set and alternating between the two.
- Reinstall and restore power. Seat the cartridge firmly, lock the basket and weir back in place, then turn the power on. Never run the spa without the filter in place.
The filter soak: what to use
Use a product sold as a spa or hot tub filter cleaner and follow its label for dilution and soak time. If your spa uses a biguanide sanitizer such as Baquacil, Unicel says the cartridge needs a biguanide specific cleaner first, before any standard cartridge cleaner. Some brands put a mineral cartridge inside the filter; Master Spas says not to soak its EcoPur core because it can deactivate the minerals. Read your manual before the cartridge goes into the bucket.
What not to do
- No pressure washer. Master Spas says high pressure can damage the filter fibers. A garden hose is enough.
- No dishwasher. Master Spas says the heat and harsh detergents can damage the filter and leave residue that affects water chemistry.
- No acid wash as routine. Unicel calls acid washing perhaps the biggest single cause of premature cartridge failure and says never to do it without degreasing first.
- No skipping the manual. Caldera specifies a filter degreaser. Canadian Spa Company says its spas require genuine Canadian Spa Co. filters, and that non genuine filters void the warranty.
Safety first
Wear rubber gloves and eye protection with filter cleaners, work in a ventilated space, keep the bucket away from kids and pets, and follow the label. Unicel’s instructions call for gloves and safety glasses when using acid or chlorine and warn never to mix them. Any electrical work, such as a breaker or GFCI that keeps tripping, belongs to a licensed electrician, and local code has the final word.
Signs a cartridge is worn, not just dirty
Cleaning cannot fix physical damage. Look for:
- Flat, frayed or misshapen pleats, or discoloration that stays after a full soak (both are replacement signs per Master Spas).
- Cracked end caps. Unicel says clogged media is the most common cause on used cartridges: pressure builds and the cap bends until it cracks.
- A crushed or collapsed core, which Unicel ties to running a cartridge that has not been cleaned often enough.
- Flow problems right after cleaning, such as weak jets or a flow error, when water level and valves check out.
One thing that is not a reason to replace: Unicel says a cartridge works fine even with broken or missing pleat bands.
What a dirty filter does to your tub
A clogged cartridge restricts flow. Caldera says that can hurt jet performance and trip the high limit thermostat, which turns off the entire spa. If your tub stopped heating, clean the filter first, then work through our hot tub not heating guide.
Hot tub filter replacement: how to measure and match
The safest match is the part number from your tub maker. Unicel says its end caps are marked with one part number, and Caldera says the right cartridge size for each Paradise model is listed in the back of its manual. If the number has worn off, record:
- Length, end cap to end cap.
- Outside diameter.
- Top and bottom fittings: open hole, threaded, handle, or closed cap, and the thread size if there is one.
- Filter area in square feet, if printed on the label, plus how many cartridges your tub uses.
The Pleatco cartridge finder on Pentair’s Pleatco page searches by part number, by manufacturer, or by diameter and length. For a tub under warranty, buy from the maker’s dealer: Canadian Spa Company lists its support site (support.canadianspacompany.com) and 1-877-909-7727 in the Toronto SE manual.
Filter details on the tubs we sell
We do not sell hot tub filters, spa filter cartridges, filter cleaners or spa chemicals. For those, go to your tub maker’s dealer or buy a cartridge with the matching part number. What we can show you is how filtration is listed on some of the hot tubs we carry. Prices are as listed at the time of writing and can change.
| Hot tub | Listed filtration | Listed price |
|---|---|---|
| Canadian Spa Yukon 2-Person 16-Jet Plug and Play KH-10136 | 35 sq ft open antimicrobial filter, plus ozone generator | $7,749 |
| Canadian Spa Toronto SE 6-Person 44-Jet KH-10143 | Not listed (the owner’s manual lists a 100 sq ft Glacier Antimicrobial filter set, KA-10032) | $12,749 |
| Canadian Spa Grand Bend 94-Jet 9-Person KH-10152 | 2 x 50 sq ft Antimicrobial Glacier with silver ions (100 sq ft) | $22,750 |
| Cal Spas Aloha PZ-614L | Teleweir filter system (Bio-Clean), 15 sq ft | $6,050 |
| Cal Spas Tropical EC-751B | Filter system (Bio-Clean), 75 sq ft UltraWeir | $10,990 |
| Cal Spas Newporter EC-1148LX | Filter system (Bio-Clean), 100 sq ft (2 x 50 sq ft) | $17,650 |
A two cartridge tub means two to clean and two to replace, so budget for a spare set. See the full Canadian Spa Company range for other models. If you are shutting a tub down for the season, our guide to winterizing a hot tub covers what to do with the filter during closing.
Frequently asked questions
How long should a filter soak last?
As long as your filter cleaner’s label says. Caldera’s manual defers to the package directions, Master Spas describes traditional cleaners as an overnight soak, and Unicel’s care page says at least one hour, with overnight more effective.
Can I clean a hot tub filter with just water?
A hose rinse removes loose debris and is fine between deep cleans. It does not remove oils and minerals, which is why Caldera says to always use a filter degreaser for the full clean.
When is hot tub filter replacement due?
Replace on your manufacturer’s schedule (our maintenance guide has the intervals) or sooner if you see frayed or flattened pleats, cracked end caps or a crushed core.
Need help with your hot tub?
Call us at 866-777-2590, Monday to Friday, 9 AM to 6 PM PST, and we will help you find the filter details for the tub you own or are considering. Orders of $999 or more ship with free freight shipping. For returns, see our return and refund policy.
