Glacier AO3P Filtration: How Our Hot Tub Water Stays Cleaner With Up to 80% Less Chlorine

Hot tub water care doesn’t have to mean swimming-pool chlorine levels and constant chemical dosing. Our Glacier AO3P filtration system combines four complementary technologies to keep spa water clear, hygienically clean and gentler on your skin, with significantly fewer chemicals than a traditional setup. This guide explains how the four parts of the system work together, what AO3P actually stands for, and what it means for your weekly water care routine.

What “AO3P” stands for

AOP, short for Advanced Oxidation Process, is a water-treatment approach that combines multiple oxidisers to break down contaminants more effectively than any single chemical or treatment can on its own. Most commonly that means pairing ozone (O₃) with ultraviolet (UV) light, which together produce hydroxyl radicals, extremely short-lived but powerful oxidisers that can break down organics and inactivate bacteria the way chlorine alone can’t. The “AO3P” branding reflects this combined ozone (O₃) plus UV plus filtration approach.

1. Antimicrobial filters

The first line of defence is the filter cartridge itself. Standard spa filter media physically traps particles down to about 5–10 microns, fine enough for most debris, but the surface of the filter can still become a place where bacteria settle and grow between cleanings.

Glacier filters are built with antimicrobial protection in the pleated media itself, plus silver-ion technology embedded in the end caps. Silver ions inhibit bacterial growth on the cartridge, so the filter is effectively self-protecting between cleans. The practical benefit: the filter stays cleaner longer, lasts longer, and the inside of the hot tub gets the benefit of a continuously antimicrobial-treated cartridge running 24 hours a day. It’s one of the most current technologies in spa filtration today.

2. Ozone generator

The ozone generator produces ozone (O₃) on demand through electrical ionisation and injects it into the spa’s plumbing. Ozone is one of the most powerful natural oxidisers, it breaks down body oils, lotions, sweat residues and many bacteria much faster than chlorine alone, and it leaves no chemical residue (it reverts to ordinary oxygen as it does its work).

The system runs in the background while you’re not using the tub, oxidising what comes off bathers between sessions and keeping the water visibly cleaner with no manual input from you.

3. UV light and AOP3

The UV light sits inline with the plumbing and exposes the water to ultraviolet light at a specific wavelength as it circulates. UV alone disinfects the water by damaging the DNA of bacteria and viruses passing through the chamber.

Combined with the ozone generator, the UV light triggers the formation of hydroxyl radicals, this is the AOP part of “AO3P”. Together they target some of the most resistant pathogens that survive chlorine alone, including Cryptosporidium, a chlorine-resistant parasite that can survive in pool and spa water for days. The combination is more effective than chlorine alone against these particular pathogens, which matters in any shared water.

4. Chemicals, but a lot less of them

Because the antimicrobial filters, ozone and UV are doing most of the heavy lifting, the chemical side of water care can be dialled right back. With Glacier AO3P running, you can use much less chlorine than you would on a traditional spa setup.

You’ll still need some chemistry, chemicals aren’t there just to sanitise. They also keep the pH and alkalinity in range, prevent scale, and break down body oils that filtration doesn’t catch. We recommend chlorine granules or bromine granules as your primary sanitiser at the reduced dose. The result: water that’s gentler on skin and eyes, less aggressive on swimwear, and noticeably less effort to keep balanced week-to-week. To see why chlorine is our recommended sanitiser, read our guide to chlorine or bromine for your hot tub.

What the system means for UK owners

For UK owners, AO3P filtration translates into several practical wins:

• Less chemical handling. Less chlorine measured out, less storage in the garage, less smell.
• Gentler water. Lower chlorine levels mean less stinging eyes after a soak and less impact on skin and swimwear.
• Cleaner water for longer. Continuous oxidation between sessions means the water doesn’t go off as quickly between water changes.
• Less filter wear. Antimicrobial filters last longer and need less frequent replacement.
• Easier weekly routine. Less manual chemistry means less time spent on water care each week.

This is one of the reasons modern Canadian Spa hot tubs are notably easier to live with than older or cheaper spas, the water-care system is genuinely more efficient, not just nominally fancier.

Frequently asked questions

Does Glacier AO3P mean I don’t need any chlorine?

No, some sanitiser is still essential, just much less of it. Plan for around 20% of the dose you’d use on a non-AO3P spa, alongside regular pH and alkalinity balancing.

How long do Glacier filters last?

Replace a Glacier cartridge every 6 months for best performance, or up to 12 months for economy, and sooner with heavy use. Rinse it every 2 to 3 weeks and soak it in filter cleaner monthly in between. Replace it straight away if flow noticeably drops or the pleats look damaged.

Does the UV bulb need replacing?

Yes. UV bulbs lose effectiveness over time even when they still appear to be working. Replace per the system’s recommended interval (typically annually) to keep the UV component performing properly.

Is Glacier AO3P safe for sensitive skin?

Many owners with sensitive skin find AO3P-equipped spas more comfortable than traditional chlorine-heavy setups precisely because the chlorine load is much lower. As with any product, individual experiences vary; if you have specific skin conditions, speak to your GP before starting regular spa use.

Will it keep the water clear if the spa isn’t used for a few weeks?

The continuous ozone and UV cycle helps, but extended periods without bathers means filtration is doing little work. For longer absences, drop the temperature slightly and check chemistry on return, you may need a small shock dose to refresh the water.

Looking for replacement filters? Browse Glacier filters here, or pair them with our filter cleaning brush and filter cleaner to make every cartridge last longer.

How water moves through the system, step by step

1. Pre-filter. Water first passes the fine mesh pre-filter on top of the Glacier cartridge, which catches hair, grit and larger debris.
2. Glacier cartridge. The M-pleat media traps fine particles. The antimicrobial material and silver ion end caps stop bacteria building up on the filter.
3. Pump and heater. Filtered water is pumped through the heater.
4. Ozone. Ozone is injected into the water to oxidise oils and organic matter.
5. UV chamber. UV light treats the water, and with ozone forms the advanced oxidation step.
6. Back to the spa. Treated water returns through the jets, where the low level of sanitiser keeps protecting it between cycles.

Why less chlorine is needed

Chlorine in a spa does two jobs: it kills bacteria, and it is used up breaking down oils, sweat and other waste. In a standard spa, chlorine does most of that second job too, so you need to keep adding it. In a Glacier AO3P spa, ozone and UV take on much of the breakdown work, and the filter stops bacteria living on the cartridge. The chlorine is left mainly for keeping a protective level in the water, so the dose falls. How much less you use depends on bather load, how often you soak and how well the water is balanced.

Keep free chlorine within the range your test shows as correct for your spa, and keep pH at 7.2 to 7.6 and total alkalinity at 80 to 120 ppm. Sanitiser works much less well when pH is high.

Maintenance schedule

When	Task
Weekly	Test the water with the Water Test app; rinse the pre-filter
Every 2 to 3 weeks	Rinse the Glacier cartridge with a hose
Monthly	Soak the cartridge in filter cleaner, then rinse well
Every 3 to 4 months	Drain, clean the shell and refill
Every 6 months	Replace the Glacier cartridge for best performance (up to 12 months for economy, sooner with heavy use)

How many filters your spa needs

Glacier 50 sq ft filters	Models (purchased after 2014)
One	Calgary, Cambridge, Gander, Kelowna, Manitoba, Montreal, Muskoka, Okanagan, Saskatoon, London SE, Erie SE
Two	Alberta, Grand Bend, Halifax, Kingston, Niagara, Ottawa, Quebec, Thunder Bay, Toronto SE, Vancouver, Victoria, Winnipeg

The Glacier 50 sq ft filter comes with a pre-filter screen. Check your manual if your spa was bought before 2014.

More questions

Can I use non-Glacier filters?

The Glacier filter fits the Mountain Pure filtration system in our spas. A filter without antimicrobial media will still filter, but you lose that part of the system.

Do I still need to shock the water?

Yes, after heavy use or if the water looks dull. The app tells you when.

Should I soak and replace both filters at the same time?

Yes, on two-filter spas it keeps flow even and makes the schedule easy to remember.