How to Clean a Hot Tub Filter Cartridge (and How Often)

Last updated: September 2026

Your filter cartridge is the hardest-working bit of kit in your hot tub. It catches the fine stuff that gets past the skimmer basket: hair, skin, body oils, pollen and the grit that makes water look dull. When it’s clogged, your water goes cloudy, your sanitiser has to work harder, and your pump struggles. In a spa pack you may even get a flow error.

The good news is that cleaning one is easy, cheap and takes about ten minutes of actual work. Here’s how I do mine, and how often.

How often should you clean a hot tub filter?

Most manufacturers recommend a fairly tight routine. Jacuzzi and Master Spas both say rinse weekly and use filter cleaner monthly. Here’s the schedule I follow:

How often	What to do	Time
Every 1–2 weeks (weekly if the tub is busy)	Take it out, hose between the pleats, and check the skimmer basket	5–10 minutes
Monthly	Spray-on or short soak with spa filter cleaner, then rinse	20–30 minutes
Every water change (about every 3–4 months)	Overnight soak in filter cleaner, and descale if needed	Overnight
Every 12–24 months	Replace the cartridge

Use is what really matters. A tub that gets used every night with guests needs more than one that’s used on a Friday. If your water is going dull, foam is appearing or flow feels weak, clean the filter first. It’s the cheapest fix there is. The deep clean fits neatly with a drain and clean of the tub, and the whole routine is in my beginner’s guide to hot tub maintenance.

Got a pressure gauge? Use it

Most DIY builds (and pools) have the cartridge in a separate filter housing in the control room, often with a pressure gauge on top. Note the reading with a clean cartridge. A common rule of thumb from Trouble Free Pool is to clean when the pressure is about 25% above that clean reading. If it climbs back up within a few days of a good clean, the cartridge is worn out.

What you’ll need

• A garden hose with a normal spray nozzle
• A bucket or tub big enough for the cartridge (a tall one if you can)
• Spa filter cleaner, either a spray, a soak or tablets
• Rubber gloves and eye protection
• Silicone lubricant for the O-ring (for housings)
• A spare cartridge, ideally

Step by step: how I clean my filter cartridge

1. Turn the power off

Don’t take the filter out with the pump running. On a shop-bought tub, switch it off at the isolator. On a DIY tub with a separate housing, switch the pump off, close the isolation valves either side of the filter, and open the air bleed on top to release any pressure before you undo the lid.

2. Get the cartridge out

Depending on the brand, there’s usually a clamp ring, lid or a fastener at the bottom that needs removing before the lid comes off. It can be quite tight. My control room is tight on space, so I actually take the whole filter housing out when I do a cartridge clean. That’s one of the reasons I say to make your control room bigger than you think you need. There’s more in hot tub control room design considerations.

Once the top is off, you can get at the cartridge. Look how manky this one was!

3. Hose off the loose dirt

Stand it in a bucket (it makes getting rid of the dirty water easier) and hose it from the top down. Hold the nozzle at an angle and work between each pleat, not just across the outside. A normal garden hose nozzle is plenty. Don’t use a pressure washer. It frays the filter fabric and opens up the pores, so the filter lets more through afterwards.

4. Soak it in filter cleaner

For the monthly clean, a spray-on cleaner left for 15–20 minutes and then rinsed off is enough. For the deep clean, I soak mine in cartridge cleaner for 8–12 hours. Master Spas says overnight, and Jacuzzi says 12–24 hours. The soak breaks down the body oils, lotions and grease that a hose can’t shift, and it kills off the bacteria that build up in the pleats.

If, like me, your bucket isn’t big enough to cover the whole filter, flip it over after the first 8–12 hours and soak the other end.

5. Descale only if you need to, and only after degreasing

If you live in a hard-water area and the pleats feel crunchy or look chalky, the filter may need descaling as well. Always degrease first. As Trouble Free Pool puts it, acid on a greasy filter solidifies the grease, and that can ruin the cartridge. Jacuzzi suggests diluted white vinegar (about 1 part vinegar to 3–4 parts water) for mineral deposits, or use a descaler made for filters.

6. Rinse thoroughly

Rinse every bit of cleaner out. Leftover filter cleaner in the pleats is a classic cause of foam when the cartridge goes back in. See foam in a hot tub.

7. Check the O-ring and housing

This is also a good time to give the O-rings and the filter housing a good clean with the hose. Check the O-ring for cracks or flattening, and give it a light wipe of silicone lubricant (not Vaseline, which can swell rubber seals). A dry or pinched O-ring is a common cause of a drip, or of air being sucked in on the suction side.

8. Let it dry if you can, then refit

Drying fully between cleans helps the fabric last longer and knocks back any biofilm, so Jacuzzi and Master Spas both suggest keeping two cartridges and swapping them. Refit, open the valves, bleed the air out of the housing, and check for leaks. If the pump sounds rough or the jets are weak afterwards, you may have trapped air. See how to deal with a hot tub air lock.

Common mistakes that kill filters early

• Pressure washers or a jet nozzle held too close. They shred the fibres.
• The dishwasher. The heat and detergent damage the filter. Both Jacuzzi and Master Spas say don’t.
• Bleach, washing-up liquid or laundry detergent. These damage the fabric or leave residue that foams. Use a product made for spa filters.
• Acid before degreasing, which bakes the oils in.
• Running the tub without a filter “just for a day” while one dries. That’s what the spare is for.
• Chlorine tablets inside the cartridge. Concentrated chlorine sitting against the fabric can damage it. Use a floating dispenser.
• Buying the wrong size. Match the length, diameter and end-cap type (open hole, threaded, handle) exactly. Take the old one or its part number with you.

When to replace your filter

Manufacturers generally say around a year, with well-maintained filters lasting 12–24 months. For a busy tub, 12 months is a safe default. Replace it sooner if:

• The pleats are flat, frayed, torn or discoloured even after a deep clean
• The end caps are cracked or the core is split
• Pressure or flow problems come back within days of cleaning
• The water won’t stay clear despite good chemistry

If you’re running two cartridges and alternating them, they’ll each last longer. Just keep a note of when you bought them.

Troubleshooting

Symptom	Filter-related cause	Fix
Cloudy water	Clogged or worn cartridge, or it’s not seated properly so water bypasses it	Clean or replace it, check the seating, and check your chemistry
FLO or flow error, weak jets	Restricted filter	Clean the filter, then see hot tub FLO error
Foam after cleaning	Cleaner or detergent left in the pleats	Rinse again, more thoroughly
Housing drips or leaks	Dirty, dry or damaged O-ring	Clean, lubricate or replace the O-ring
Filter pressure high straight after a clean	Worn-out cartridge, or scale in the fabric	Descale (after degreasing) or replace it

If the water still won’t clear, work through my guide to hot tub chemical levels and cloudy water in a hot tub.

Cartridge or sand filter on a DIY tub?

Most shop-bought hot tubs use cartridges. On a DIY build you have a choice. Cartridges filter finer and are easy to service. Sand filters need backwashing (which wastes water), but they cope well with bigger volumes. I’ve covered the pros and cons in cartridge or sand filter: which is right for me? and can I use a sand filter on my DIY hot tub?

Need a new cartridge or O-ring?

Replacement cartridges, housings and O-rings are all at parts4tubs.co.uk in the UK and parts4tubs.com in the USA. Measure your old one (length, diameter and the size of the centre hole) before you order. If you’re still planning a build, my DIY hot tub plans include the full plumbing layout and parts list, filter included. Just leave yourself room to get the filter out without dismantling half the control room like I do.

FAQs

How often should I clean my hot tub filter?

Rinse it every week or two, use filter cleaner monthly, and give it a deep overnight soak at each water change (roughly every three to four months). Clean it more often if the tub gets heavy use.

Can I clean a hot tub filter with a pressure washer?

No. It damages the filter fabric. Use a garden hose with a normal nozzle and work between the pleats.

Can I put a hot tub filter in the dishwasher?

No. Manufacturers including Jacuzzi and Master Spas warn that the heat and detergent damage the filter, and the detergent residue can cause foam.

Can I use vinegar to clean a hot tub filter?

Diluted white vinegar is fine for mineral scale, after you’ve degreased the filter with a proper cleaner. It won’t remove oils on its own.

How long do hot tub filters last?

Usually 12–24 months with good care. Replace a filter sooner if the pleats are damaged or it clogs again within days of cleaning.

Can I run my hot tub without a filter?

Not for any length of time. Debris goes straight to the pump and heater, and the water won’t stay clear. Keep a spare to swap in.

How often do you clean yours? Let me know in the comments below. I read them all.

Cheers,
Andi

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Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi