Essential Hot Tub Maintenance Checklist (UK Step-by-Step)

Hot tub maintenance checklist: test water twice weekly, keep pH 7.2-7.6, rinse filters weekly, and drain every 3-4 months. UK step-by-step routine.

The essentials in one line: test your water at least twice a week, hold pH between 7.2 and 7.6 with sanitiser at 3-5 mg/l (chlorine) or 4-6 mg/l (bromine), rinse the filter weekly, and fully drain and refill every 3-4 months. Do those four things consistently and you prevent the vast majority of cloudy water, biofilm and equipment faults that catch UK hot tub owners out.

Most breakdowns and green-water disasters are not bad luck – they come from skipped or guessed-at maintenance. This checklist turns spa care into a predictable weekly, monthly and seasonal routine, with the exact numbers, timings and products you need. It is written for UK conditions, including hard-water regions and cold winters, and follows the risk-based approach recommended in HSE guidance (HSG282) for managing spa water safely at home.

Quick-Reference Routine

How often	What to do
After each use	Skim debris, wipe the waterline, and replace the cover.
2-3 times a week	Test pH, sanitiser and alkalinity; adjust as needed and add sanitiser.
Weekly	Rinse the filter, shock the water, and check total alkalinity (80-120 mg/l).
Monthly	Deep-soak the filter overnight; inspect jets, seals and the cover.
Every 3-4 months	Drain, clean the shell, flush the pipework, and refill through a pre-filter.
Every 12-18 months	Replace the filter cartridge; book a service check if needed.

Step 1: Gather Your Hot Tub Maintenance Supplies

Good maintenance starts with having the right kit within arm's reach, so testing and dosing take minutes rather than becoming a chore you put off. Assemble a dedicated, waterproof caddy near the spa with everything below.

• Test strips or a photometer: a reliable 6-in-1 test strip pack covers free chlorine, bromine, pH, total alkalinity, cyanuric acid and hardness. For precise results, a liquid or photometer kit is worth adding.
• Sanitiser: chlorine mini tablets in a floating dispenser, or bromine granules if you prefer a lower-odour, more pH-stable option. Not sure which suits you? See our guide on chlorine vs bromine for UK hot tubs.
• Balancers: pH increaser and reducer, total alkalinity increaser, calcium hardness increaser, and a non-chlorine shock for regular oxidising.
• Cleaning tools: a skimmer net, a soft-bristled brush, non-abrasive surface cleaner, and filter cartridge cleaner.
• Scale control: in hard-water areas (much of the South East and Midlands), a scale inhibitor protects the heater and pipework.
• A spare filter: keep a second spa filter cartridge so you can rotate one while the other dries.

New to spa ownership? Our hot tub care for beginners guide walks through the basics before you build your routine.

Step 2: Test Water Chemistry Regularly

Water testing is your first line of defence, and it only takes a couple of minutes. Test at least twice a week, and daily if the tub is used heavily or by several people. Testing tells you whether the water is safe, whether your sanitiser is actually working, and whether balance issues are quietly attacking your equipment.

Aim for these UK target ranges:

• pH: 7.2-7.6 (ideally 7.4-7.6). Above 7.8, chlorine loses effectiveness and scale forms; below 7.2, water becomes corrosive and irritating.
• Free chlorine: 3-5 mg/l (ppm), or bromine: 4-6 mg/l.
• Total alkalinity: 80-120 mg/l – this buffers pH and stops it swinging. Adjust alkalinity first, then pH.
• Calcium hardness: 150-250 mg/l to avoid both scale and foaming.
• Cyanuric acid (stabiliser): keep below 30-50 mg/l for spas; too much locks up your chlorine.

For a fuller explanation of why each reading matters, see the benefits of regular water testing. Below is a quick troubleshooting reference for the most common issues.

Problem	Likely cause	Fix
Cloudy water	Low sanitiser, high pH, or a tired filter	Test and rebalance, shock, and clean the filter
Strong chlorine smell	Chloramines from under-sanitising	Shock the water; hold free chlorine at 3-5 mg/l
Skin or eye irritation	pH out of range or over-dosing	Bring pH to 7.2-7.6 and let levels settle before use
Scale or scum line	High calcium/pH or hard water	Use a scale inhibitor; wipe the waterline
Foaming	Lotions, oils, or low calcium	Add anti-foam short-term; refresh water if persistent

Step 3: Clean Filters and Replace When Necessary

Your filter does the heavy lifting, trapping skin cells, oils and debris that would otherwise feed bacteria and cloud the water. Neglect it and you overwork the pump and heater.

• Weekly: remove the cartridge and rinse between the pleats with a garden hose at moderate pressure. Avoid a pressure washer, which shreds the fibres.
• Monthly: soak the cartridge overnight in a diluted filter cleaner to dissolve oils and mineral scale that rinsing leaves behind, then rinse thoroughly and let it dry fully before refitting.
• Every 12-18 months: replace the cartridge. Sooner if you see flattened or brittle pleats, cracks in the end caps, reduced flow, or water that stays cloudy after cleaning.

For a step-by-step method and tips on rotating two cartridges, read our hot tub filter cleaning guide.

Step 4: Inspect and Maintain Equipment Components

A quick monthly inspection catches small faults before they become expensive. Work through the visible components methodically.

• Electrical safety: confirm the tub is on an RCD-protected supply and test the RCD monthly using its test button. Any electrical work must be done by a qualified electrician.
• Seals and jets: apply a silicone-based lubricant to O-rings and gaskets; run each jet to check for consistent pressure and no grinding or rattling.
• Heater and pipework: look for scale on the heater element and inspect unions and pipe joints for leaks or corrosion.
• Cover: check for waterlogging or splits – a saturated cover wastes heat and can strain lid lifters. A well-fitted cover is the single biggest factor in running costs.
• Listen: new squeals, hums or clicks from the pump usually mean a bearing or airlock issue worth investigating early.

Keep a simple maintenance log of dates, readings and anything you notice; the pattern over time makes faults far easier to diagnose. A professional service every 12-24 months is a sensible backstop.

Step 5: Drain and Refill the Hot Tub Periodically

Even with perfect dosing, dissolved solids (TDS) build up over time and water eventually resists balancing. As a rule of thumb, drain and refill every 3-4 months, or use the simple formula: litres of water ÷ (3 × number of daily bathers) = days between changes.

1. Before draining: add a pipe/system flush and run the jets for 20-30 minutes to clear biofilm from the plumbing, then switch off the power.
2. Drain: use the drain valve or a submersible pump, directing water away from foundations and borders.
3. Clean: wipe the empty shell with a non-abrasive spa cleaner, paying attention to the waterline, jet surrounds and footwell. Inspect for cracks while it is empty.
4. Refill: fill through a hose pre-filter to reduce metals and hardness, filling through the filter housing to avoid an airlock.
5. Rebalance: set alkalinity, then pH, then sanitiser, and shock the fresh water. Let it circulate and reach temperature (typically 37-38°C) before use.

Planning to leave the tub unused over winter? Follow our step-by-step winterising guide to prevent frost damage to pipes and pumps.

Step 6: Verify Overall System Functionality

Finish each major service with a full functional check so you know the spa is safe and ready.

• Controls and heating: confirm the set temperature is reached and held; a slow recovery after use can signal a flow or heater issue.
• Circulation: run every jet and pump speed, checking for steady flow and no air surging.
• Safety devices: re-test the RCD and any high-limit cut-outs.
• Final water test: confirm pH 7.2-7.6 and sanitiser in range before anyone gets in. If free chlorine is above 5 mg/l, wait for it to fall back into range first.

Frequently Asked Questions

How often should I test my hot tub water?

Test at least two to three times a week, and daily during heavy use. Keep pH at 7.2-7.6, free chlorine at 3-5 mg/l (or bromine at 4-6 mg/l) and total alkalinity at 80-120 mg/l.

What temperature should a hot tub be in the UK?

Most owners set 37-38°C. The maximum recommended is 40°C; higher is unsafe, especially for children, pregnant users and anyone with heart conditions. Lowering the temperature a few degrees when the tub is unused also cuts running costs.

How often should I drain and refill my hot tub?

Every 3-4 months for typical home use, more often if it is used heavily. Rising total dissolved solids and water that will no longer hold its balance are the usual signs it is due.

Why does my hot tub water keep going cloudy?

Usually low sanitiser, high pH, a clogged filter, or a build-up of oils and lotions. Rebalance the water, clean the filter, and shock with a non-chlorine oxidiser. If it persists after a full clean, it is time to drain and refill.

Is chlorine or bromine better for a hot tub?

Both are effective. Chlorine acts fast and is lower cost; bromine is more stable at the higher temperatures of a spa and gentler on the nose. See our chlorine vs bromine comparison to choose.

Keep Your Water Clear With ClearSpa

Follow this routine and clear, safe water becomes the norm rather than a battle. ClearSpa supplies the tested UK chemicals, filters and cleaning essentials referenced throughout this checklist – from 6-in-1 test strips and non-chlorine shock to filter cartridge cleaner and replacement cartridges. Stock your maintenance caddy once and your weekly routine takes minutes.