Cleaning a Hot Tub Filter Properly

Hosing a filter is not cleaning it. A hose removes the visible debris sitting on the surface of the pleats and leaves behind the oils and fine particles bound into the media, which is the material actually restricting flow. That is why a filter can look clean and still be doing very little.

Cleaning one properly means soaking it, and soaking takes hours rather than minutes. Which is the single most useful thing to know about filter maintenance, because it changes how you plan it.

Not sure where your water is? Check your readings.

What the filter is actually holding

Two different things end up in filter media, and they need different treatment.

Particulate is hair, skin cells, leaf fragments, grit and dust. It sits in and between the pleats, and a rinse removes most of it.

Oils are body oil, lotion, sunscreen and detergent residue. These bind to the media rather than resting on it, and no amount of water pressure shifts them. They are also what feeds biological growth, which is why a filter that has never been soaked is the usual source of a musty smell.

A filter loaded with oils passes water through without removing much, so the particles stay in circulation. That shows up as cloudy water that builds gradually over weeks and worsens after heavy use.

The three levels of cleaning

Rinse, weekly

Remove the filter and rinse with a hose, working between each pleat rather than spraying across the surface. Fan the pleats apart with your fingers as you go. Five minutes.

This handles particulate only. It is maintenance between real cleans, not a substitute for them.

Soak, every two weeks

This is the one that matters. Use a filter cleanser in a bucket of water, submerge the filter completely, and leave it for at least a couple of hours. Overnight is better.

Then rinse thoroughly, and keep rinsing longer than feels necessary, because cleanser left in the media goes straight into your water and can cause foaming on the next fill.

Never soak a filter in the tub itself. Whatever comes out of the media ends up in the water, which is precisely what you were trying to remove.

Replace, when it stops recovering

Media does not last forever. Pleats lose their shape, the material degrades, and eventually a filter cannot be brought back regardless of how it is cleaned.

Signs it is finished: pleats that stay flattened after cleaning, visible tears or gaps, an end cap that has come loose, or water quality that no longer improves after a proper soak. Most cartridges last a season or two depending on use.

Why a spare filter changes everything

The reason most filters are hosed rather than soaked is practical. A soak takes hours, and a filter needs to be dry before it goes back in, so a proper clean means the tub is out of service overnight.

Keep two filters and that disappears. Swap the clean one in, soak the dirty one at your own pace, let it dry fully, and it is ready for the next rotation. The cost of a second cartridge is small against the benefit of never having a reason to skip the real clean.

Drying matters more than people expect. Media that goes back damp is an invitation for growth, and that is where musty smells start.

What not to do

• No pressure washer. It drives debris deeper into the media and damages the pleats. Hose pressure is enough
• No dishwasher. Heat warps the plastic and detergent residue is very difficult to rinse out
• No household detergent or bleach, which leaves residue that foams and can degrade the media
• No stiff brush. It tears the pleats, and a torn filter passes water without filtering it
• No soaking in the tub, for the reason above
• No putting it back wet, if you can avoid it

If a filter has come out of water with a heavy chemical imbalance, or from a tub that had a fouling event, replace it rather than trying to recover it.

How the filter connects to everything else

A neglected filter shows up as several problems that look unrelated.

• Cloudy water, because particles are staying in circulation rather than being removed
• Foam, because the oils held in the media are exactly what causes it, and some release back into the water
• Musty smell, from growth in damp, oil-rich media
• Sanitizer that will not hold, because organic material left in circulation consumes it
• Weak circulation, which is the most direct symptom and the easiest to notice

Which is why the filter is worth checking early when troubleshooting anything, rather than after you have added products. It is often the whole answer, and it costs nothing.

A routine that works

• Weekly: rinse, working between the pleats
• Every two weeks: soak in a filter cleanser, rinse thoroughly, dry fully
• Monthly: inspect for tears, flattened pleats and loose end caps
• With every water change: soak, and start the new fill with a clean filter
• Each season: assess whether the cartridge is still recovering, and replace it if not

Adjust for use rather than following it rigidly. A tub used daily by four people needs more attention than one used twice a week by two.

The other half of the job is reducing what reaches the filter in the first place. Rinsing off before getting in removes the oils that cause most of the loading, and keeping the cover on keeps the debris out.

If you have an AlumiTub

Filtration is included on Electric and Hybrid models, and available as a plug-and-play add-on for a Wood Fired. A Wood Fired without that add-on has no filter, so none of this applies and the water is managed by changing it instead.

Where filtration is fitted it is a 50 micron sediment filter, and it is what holds a single fill for three to four months rather than a week or two. Keeping it clean is what protects that interval, so a filter neglected for a season is quietly costing you water changes.

The equipment sits inside the cedar steps against the tub, so the filter is reachable by hand without dismantling anything. Two capfuls of filter booster in the canister monthly, and a cleanser soak every two weeks, is the whole routine.

Use the filter cleanser rather than a general product, and rinse thoroughly. Good Clean Living Water Care includes both the cleanser and the booster.

Not sure where your water is? Check your readings.