Hot tub maintenance: water balance, filters and an easy routine

By the Fonteyn UK team · Outdoor living advisers at Fonteyn

Hot tub maintenance comes down to three easy habits: balance the water, keep pH between 7.2 and 7.6, and clean the filter cartridges on a simple schedule.

Get those into a rhythm and the water stays clear, soft and inviting all year round. The rest of this routine takes only minutes a week.

How do you keep hot tub water balanced?

Water balance is simply about keeping a few easy numbers in a comfortable range. The first is pH, which measures how soft or sharp the water feels. The sweet spot is 7.2 to 7.6, and within that band the water feels lovely against the skin and the sanitiser does its job well. Test strips read pH in seconds, so a quick dip two or three times a week is all it takes.

Total alkalinity is the quiet helper behind a steady pH. Kept between 80 and 120 parts per million, it acts like a cushion that holds the pH in place between tests. According to NHS guidance on pools and spas, well-managed water with the right balance keeps bathing safe and comfortable for everyone who uses it. A monthly alkalinity check is plenty for most households.

When a reading drifts, a small scoop of pH up or pH down brings it back. The advisers at Fonteyn suggest adding a little, running the pump to circulate, then retesting after thirty minutes. Modern spas make this even simpler. Passion Spas builds in Synergy Water Care on its Signature and Exclusive ranges, which pairs steady filtration with ozone and UV treatment so the water is polished continuously and far less sanitiser is needed to keep it sparkling.

Which sanitiser suits a hot tub best?

A sanitiser keeps the water fresh and hygienic, and there are three popular ways to do it. Chlorine is the classic choice, working quickly and reading easily on a test strip at around 3 to 5 ppm. Bromine is a softer option that copes beautifully with the warm temperatures of a hot tub, holding its strength steadily and producing very little scent. Both are widely used across the UK and suit slightly different routines.

Then there is the modern approach: an ozone and UV system that treats the water as it circulates. This polishes the water around the clock and means the chemical top-up is light and occasional. The table below lays out all three as options to choose between, each with its own strengths, so a household can pick the one that matches how they like to look after their spa.

In the Leicester showroom, the advisers find that many owners love how little effort the ozone-UV route asks for. Synergy Water Care brings filtration, ozone and UV together on the Passion Spas Signature and Exclusive collections, keeping the water beautifully clear while the chemical routine stays light. A starter bundle of test strips and water care products makes whichever path an owner chooses simple from day one.

Fonteyn Aqua Pure Water Care

6-month supply · sanitiser, balancers and test strips · everything for one easy routine

£123

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How often should hot tub filters be cleaned?

Filter cartridges are the workhorse of clean water, catching the fine bits that would otherwise cloud the spa. A rinse under the garden hose every fortnight clears away the loose debris in a couple of minutes, fanning the pleats apart so the water runs through freely. It is one of the most satisfying small jobs an owner does, because the difference in flow is instant.

Once a month, a soak in a dedicated filter cleaner lifts out the body oils, lotions and suncream that a hose alone leaves behind. Leave the cartridge to dry, pop it back, and the filtration is as good as new. Most cartridges are happily replaced once a year, which keeps the water polished and the pumps running sweetly. A spare cartridge from the hot tub parts and water care range in the cupboard makes the swap a two-minute task.

Good spas make filtration almost invisible. Passion Spas runs a 100% filtration system, a separate low-energy pump that quietly circulates and cleans the water around the clock, working independently of the powerful massage jets. Many models also carry an EasyClean Shield finish, a smooth surface treatment that helps the shell shrug off residue so a quick wipe keeps it gleaming. Replacement cartridges and water care sit together in the Fonteyn parts range for an easy reorder.

How often should hot tub water be refreshed?

Even the best-cared-for water benefits from a fresh start now and then. Over a few months, the dissolved minerals and balancing products build up, and a clean refill brings everything back to baseline. For most households, every three to four months hits the mark, keeping the water effortless to balance and the readings nice and responsive.

There is a tidy rule of thumb for households that bathe often. Take the tub volume in litres, divide by twelve, and that gives the number of days a fill comfortably lasts. A 1,500-litre spa used by a busy family lands at around 125 days, which fits neatly into a quarterly refresh. Draining, rinsing the shell and refilling takes roughly an hour, and it is a perfect moment to deep-clean the cartridge or fit a fresh one.

After 30+ years in spas and outdoor living, the advisers at Fonteyn suggest timing a refresh with the change of season, so the spa is primed for cosy autumn evenings or bright summer mornings. UK weather makes a hot tub a year-round pleasure, and a fresh fill at the turn of the season keeps it feeling brand new. The range of hot tubs and spas shows how modern insulation and covers hold the heat right through the colder months.

What does an easy weekly routine look like?

The simplest way to keep a hot tub gleaming is to break the care into small, regular moments rather than one big session. The steps below follow that idea, building a gentle rhythm that quickly becomes second nature. None of them takes long, and each one keeps the water that bit fresher.

1. Test the water two to three times a week with a strip, keeping pH at 7.2 to 7.6 and sanitiser at a steady level.
2. Wipe around the waterline at the same time, where natural oils gather, so the shell stays bright.
3. Rinse the filter cartridge under the garden hose every fortnight to keep the flow strong.
4. Once a month, soak the cartridge in filter cleaner and check total alkalinity at 80 to 120 ppm.
5. Every three to four months, drain, rinse and refill for a clean start, and fit a fresh cartridge.

That gentle cadence is what keeps everything easy. According to NHS guidance on safe water in spas and pools, regular testing and clean filtration are the two habits that matter most, and both sit right at the top of this list. In the Leicester showroom, the advisers find that owners who settle into this rhythm rarely think about upkeep at all. A 100% filtration system does much of the quiet work between checks, and a stocked water care cupboard keeps every step ready to go.

How do you keep the cover and shell in great shape?

The cover is the unsung hero of a hot tub, sealing in warmth and keeping the water clean between dips. A wipe of the top once a month keeps it looking smart, and a UV-protectant spray a few times a year keeps the surface supple and bright through the British seasons. A clean, snug cover is also the single biggest factor in holding the heat, which keeps everything running smoothly.

That heat retention is where good insulation pays off. A well-insulated spa with a quality cover typically uses around 3 to 6 kWh a day, which at roughly 25p per kWh works out at about £25 to £45 a month, according to UK energy figures from Ofgem in 2026. Passion Spas builds three-layer insulation into its shells, wrapping the tub so the warmth stays where it belongs and the spa is always ready for a soak.

The shell itself asks for very little. A gentle wipe at each water change keeps it gleaming, and the EasyClean Shield finish on many models helps the surface stay smooth and fresh between cleans. Owners planning a cosy spa corner often pair the tub with a veranda or patio cover for shelter and shade, turning the spot into a proper year-round retreat. A quick browse of the outdoor living inspiration ideas shows how a well-placed cover and surround keep a spa beautiful for years.

Frequently asked questions

Passion Aurora

Signature collection · Synergy Water Care · 100% filtration for effortless upkeep

£13,995

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