Hot Tub Filter Cleaning & Replacement Guide

The filter is the cheapest, least glamorous part of your hot tub, and it has more influence on water quality than almost anything else. Treat it well and your sanitizer goes further, your jets stay strong, and your spa runs quietly. Neglect it and you'll see haze, foam, weak jets, and error codes within a couple of weeks.

What a Spa Filter Actually Does

Most modern spas use one or two pleated cartridge filters that look like rolls of accordion-folded fabric. As water passes through the pleats, the fabric catches particles down to about 20 microns — body oils, hair, lotions, mineral fines, dead skin, and the microscopic bits of organic debris that fuel cloudy water.

A clean filter passes water freely. A loaded filter restricts flow, which starves your heater, weakens your jets, and creates the perfect environment for biofilm to grow on the pleats themselves.

The Maintenance Rhythm

Weekly: Light Rinse

Pull the filter, rinse with a garden hose nozzle from top to bottom of each pleat for 30–60 seconds, reinstall. This takes two minutes and removes the loose surface debris before it has time to embed.

Monthly: Deep Soak

Pull the filter, rinse, then submerge in a spa filter cleaner solution (per the bottle) for several hours or overnight. The chemical cleaner dissolves oils and biofilm that simple rinsing can't touch. Rinse thoroughly afterward, let it dry, then reinstall.

Tip: keep a second cartridge on hand. While one is soaking, the other is in the spa, and you never have downtime.

Annually: Replace

Cartridge filters wear out. Pleats compress, fabric loosens, and the filter loses its effective surface area. Most last about a year of normal use; heavy-use spas need a swap closer to every 6–9 months.

Signs Your Filter Is Past Saving

• Pleats won't come clean. If a fresh soak still leaves the filter brown or slimy, the gunk has migrated deep into the fabric.
• Visible damage. Cracked end caps, separated pleats, a torn center core. Any of these mean water can bypass the filter — replace immediately.
• Loose pleat structure. Squeeze a wet filter between your hands. If the pleats compress and stay compressed, the fabric has lost integrity.
• Persistent water cloudiness. Your chemistry is balanced, you've shocked, you've drained — and water still won't clear. Tired filter is often the answer.

The Right Way to Rinse

1. Hose pressure should be firm but not blasting. High pressure can drive debris deeper into the pleats and damage the fabric.
2. Spray from the top down, working around the cartridge while rotating it.
3. Spread each pleat slightly so water reaches the bottom of the fold.
4. Rinse top-to-bottom on the inside (through the center core) as well as outside.
5. Hold the cartridge up to daylight before reinstalling. You should see light through the pleats.

What Not to Do

• Don't put filters in the dishwasher. Heat damages the plastic and breaks down pleat glue.
• Don't use household cleaners (Simple Green, bleach, etc.). Anything that foams will end up in your water. Use spa-specific filter cleaner only.
• Don't reinstall while wet without rinsing chemical residue thoroughly. You'll get foam.
• Don't run without a filter, even temporarily. The pump impeller will collect debris and the heater will scale up faster than you'd believe.

Common Filter Mistakes

The two patterns we see in the field most often:

• The "I rinse it sometimes" homeowner. Filter is loaded, jets are weak, breaker trips occasionally. Almost all of it traces back to a deep-cleaning gap that built up over months.
• The "I bought a generic cartridge" homeowner. Off-brand filters with the wrong micron rating or fitment leak water around the edges and barely filter at all. Stick with OEM or reputable aftermarket cartridges sized exactly for your model.

When We Service a Filter

Most of our maintenance visits include a filter pull and inspection. If we find it loaded, we soak it on site (or hand you a replacement off the truck) and leave you with a clean rotation. It's one of the smaller line items on a service ticket, and it has an outsized effect on how your spa runs the rest of the year.