If you own a hot tub, a test kit is not optional kit drawer clutter. The best hot tub water test kit UK owners can buy is the one they will use before every soak, read correctly in normal light, and trust enough to adjust chlorine, bromine, pH and alkalinity without guessing.
In This Article
- Best hot tub water test kit UK: quick verdict
- What a good hot tub water test kit must measure
- Best hot tub water test kits 2026 UK: our picks
- Test strips vs tablets vs digital testers
- How to read results without chasing the water
- What to buy with your test kit
- Testing routine for UK hot tub owners
- Frequently Asked Questions
Best hot tub water test kit UK: quick verdict
For most UK garden hot tubs, I would buy a decent 3-way or 4-way strip kit first, then keep a small digital pH meter only if you find colour matching hard. The boring answer is the right one: strips get used because they are quick. A posh photometer that stays in the cupboard is worse than a £9 tub of strips you use every time.
Best overall: AquaChek Chlorine Test Strips, usually about £12-£13 from Pool & Spa Centre. They are easy to find, clear enough for weekly ownership, and not so cheap that the pads feel like party confetti. If you use bromine, look for the bromine-compatible AquaChek or Blue Horizons version rather than forcing a chlorine-only strip to do a bromine job.
The best budget buy is Clearwater 3-in-1 Hot Tub, Pool and Spa Test Strips, about £9-£10 for 50 strips on Amazon UK. They cover chlorine, pH and total alkalinity, which is enough for basic inflatable hot tub ownership. They are not my favourite for fine adjustments after a refill, but they are miles better than dipping your hand in and deciding the water “looks fine”.
If you want a more serious setup, the Lovibond Scuba3s Electronic Pooltester is about £186 from Pool & Spa Centre. That is overkill for many owners, but useful if you run a holiday let, have a large hard-shell tub, or hate judging colours on a strip. I would not buy the Lovibond HSG282 Test Kit and Training Course for a normal home tub; at about £840, it is a commercial-minded route, not a Saturday-night-in-the-garden purchase.
The key is matching the kit to your water system. A chlorine hot tub needs free chlorine and pH readings. A bromine hot tub needs bromine and pH. Any tub benefits from alkalinity checks because alkalinity is what stops pH bouncing around after every tiny dose.
What a good hot tub water test kit must measure
A hot tub has a smaller water volume than a swimming pool and it runs warmer, so the readings can move fast. Two adults, body oils, a bit of fake tan, rainwater on the cover and one overexcited child can all change the water faster than new owners expect. That is why a kit needs to measure the things that actually decide whether the tub is safe and comfortable.
Sanitiser
Sanitiser is the big one. For most UK tubs that means free chlorine or bromine. If the sanitiser is too low, the water can become unsafe. If it is too high, the soak becomes harsh and you start blaming the hot tub when the real problem is overdosing.
The HSE notes that spa-pool systems are a recognised source of infectious-agent risk, which is the serious backdrop to what can feel like a small domestic chore. A home garden tub is not a leisure-centre spa, but the principle carries across: warm aerated water needs proper testing, not vibes.
pH
pH tells you whether the water is acidic or alkaline. In practice, it affects comfort, sanitiser performance and scale. Low pH can feel sharp on eyes and skin and can be rough on metal parts. High pH can make water cloudy and can make chlorine work poorly.
Most hot tub owners are aiming around pH 7.2-7.6, although your chemical system and supplier instructions matter. If your test kit only shows “low, OK, high” without useful colour steps, it is not much help when you are trying to fix a drifting tub after a refill.
Total alkalinity
Total alkalinity is the buffer behind pH. New owners often ignore it, then wonder why pH will not stay put. If alkalinity is too low, pH jumps around. If it is too high, pH can sit stubbornly high even after you add pH reducer.
For a normal UK domestic tub, I want a kit that includes alkalinity. This is why I would rather buy a reliable 3-way strip than a cheap pH-only meter as the first purchase. A pH-only reading is only half the conversation.
Calcium hardness
Hardness matters more in some parts of the UK than others. London, Kent and much of the south and east tend to have harder mains water, while parts of Scotland, Wales and the north west can be softer. Too much hardness can encourage scale; very soft water can be more aggressive to components.
You do not need to test hardness every day, but a strip kit with a hardness pad is useful after refills. If you already have a post-refill routine from our hot tub water hardness guide, use that alongside your kit rather than trying to fix everything from one strip reading.
Cyanuric acid, salt or active oxygen
These are system-specific. Stabilised chlorine products can add cyanuric acid, salt systems need salt checks, and active oxygen systems need their own compatible strips. Do not buy the cheapest strip tub in a hurry and assume it works for every sanitiser system.
If your hot tub came with a starter pack, read the label on the sanitiser first. A bromine tub needs bromine-compatible testing. A chlorine strip may show a bromine scale on the same pad, but check the bottle before trusting it.
Best hot tub water test kits 2026 UK: our picks
There are dozens of near-identical strip tubs online, and most of them look as if the same factory designed the label during a lunch break. I would keep the shortlist simple.
Best overall: AquaChek chlorine or bromine strips
Approx UK price: about £12-£16 for 50 strips, depending on version and retailer. Pool & Spa Centre lists AquaChek chlorine strips at about £12.34, and bromine or specialist variants usually sit in the same broad bracket.
AquaChek is the sensible everyday option. The colour blocks are usually easier to read than the bargain no-name kits, the tub seals properly if you actually close it, and the range covers chlorine, bromine, salt and active oxygen versions.
I would buy this if you have a hard-shell hot tub, use it several times a week, or have already had one episode of cloudy water that made you realise guessing is expensive. Pair it with our chlorine vs bromine guide if you are still choosing a sanitiser system.
Pros: clear enough for routine ownership, widely available, good range of versions.
Cons: still colour-based, so readings vary if you test in poor light or let the strip sit too long.
Best budget: Clearwater 3-in-1 strips
Approx UK price: about £9-£10 for 50 strips on Amazon UK, with larger 100-strip packs often around £19-£20.
Clearwater strips are fine for inflatable hot tubs and light home use. They usually measure chlorine, pH and alkalinity, which covers the basics for a Lay-Z-Spa or similar setup. I would not use them as my only test method for a heavily used holiday-let tub, but for a family garden tub they are useful and cheap enough to replace often.
The main weakness is that budget strips can be harder to read once the colour pads start looking close between two blocks. If you are constantly adjusting pH by tiny amounts, a better strip or a tablet kit will save faff.
Pros: cheap, easy to buy, good enough for quick pre-soak checks.
Cons: less reassuring for fine dosing, and the tub must be kept dry or the strips degrade.
Best for bromine tubs: Blue Horizons 3-Way Plus strips
Approx UK price: about £9 from Pool & Spa Centre for 50 strips.
Bromine owners need to stop buying whatever chlorine strip appears first in search results. Blue Horizons 3-Way Plus strips cover free chlorine, bromine, pH and total alkalinity, which makes them a useful simple choice if you run bromine tablets in a floater.
They are not glamorous, but neither is emptying a tub because you ignored bad readings for a week. I like them for bromine tubs because the core checks are on one strip and the price is low enough that you will not ration them.
Pros: good match for bromine or chlorine owners, cheap, simple.
Cons: not a full diagnostic kit for hardness, cyanuric acid or salt systems.
Best digital option: Lovibond Scuba3s Electronic Pooltester
Approx UK price: about £186 from Pool & Spa Centre.
The Scuba3s is the one I would consider if you are colour-blind, testing a lot, or managing water for guests. It reads with tablets rather than asking you to decide whether a pad is peach, salmon or “sort of orange”. For anyone who has stared at a strip in drizzle under a patio light, that has value.
It is expensive for a normal domestic tub, and you still need tablets, cleaning and a bit of discipline. Digital does not mean magic. Dirty sample chambers, old reagents and careless sampling can still give nonsense.
Pros: clearer readings, better for record keeping, useful for frequent testing.
Cons: high upfront price, slower than strips, more kit to maintain.
Best professional route: Lovibond HSG282-style kit
Approx UK price: about £840 for a test kit and training course package from specialist suppliers.
This is not my pick for the average reader, but it is worth mentioning because some owners land here while searching for “proper” testing. If you run a hot tub in a rental setting, have staff involved, or need formal procedures, this kind of setup starts to make sense.
For a family hot tub in a back garden, spend the money on good strips, fresh chemicals, a spare filter and a decent cover instead. If your whole test routine costs more than a budget inflatable tub, you have probably drifted into the wrong buying lane.
Test strips vs tablets vs digital testers
The best kit type depends on how often you test, how precise you need to be and how patient you are. I have a strong bias here: the right kit is the one that survives real life.
Test strips
Test strips win on speed. Dip, wait the stated time, compare the pads, then act. That makes them ideal for domestic tubs because you can test before people get in without turning water care into a lab session.
The downside is interpretation. Colour pads can be hard to read in gloomy UK weather, and people often leave the strip too long before comparing it. Once the pads keep developing, the reading becomes a suggestion, not a result.
Use strips if:
- You want fast pre-soak checks before family use.
- You own an inflatable or smaller hard-shell tub and need practical water care.
- You will replace strips regularly rather than keeping one damp tub for two years.
Avoid relying only on strips if you need written records, manage guest use, or struggle with colour matching.
Tablet and comparator kits
Tablet kits take longer but can be clearer. You add a reagent tablet to a water sample, let it dissolve, then compare the colour in a viewing block. For chlorine and pH, this can be easier than trying to judge a tiny pad on a strip.
They are less convenient, so some owners stop using them. That is the trade-off. A tablet kit kept clean and used properly can be more dependable than bargain strips, but it asks more from you.
Use tablet kits if:
- You want a better read after a refill or after heavy use.
- You keep getting odd strip results and need a second opinion.
- You are already comfortable measuring and dosing chemicals.
Digital testers
Digital testers are tempting because they look decisive. A number feels more trustworthy than a colour chart. The catch is that cheap digital pH pens are often sold as if they solve hot tub care by themselves, when they usually only measure pH and need calibration fluid.
Photometers such as the Scuba3s are more useful because they test multiple parameters with reagents. They are still not a shortcut around good sampling and cleaning.
Use digital testing if:
- You are colour-blind or find strips hard to read.
- You test often enough to justify the cost.
- You are prepared to maintain, calibrate or clean the device.
Do not buy a £12 pH pen and call it your hot tub test kit. It misses sanitiser, alkalinity and often hardness.
How to read results without chasing the water
Most hot tub water problems are made worse by overcorrection. Someone sees a slightly low pH reading, adds too much increaser, tests again immediately, sees another odd result, adds something else, and by the end of the evening the water is cloudy and everyone is annoyed.
Test from the right place
Take water from elbow depth if you can, away from the chemical floater and away from a return jet. If you grab a sample next to a dissolving bromine tablet, the reading will be skewed. Run the pumps for a few minutes first so the tub is mixed.
Read at the right time
Every strip brand gives a timing window. Follow it. Some pads need reading after 15 seconds, some after 30, some after a minute. Do not dip a strip, get distracted, then judge it after three minutes.
For outdoor tubs, natural daylight is best. Patio lights can make colours look warmer, and phone torches are not much better. If you often test at night, that is one argument for a better strip brand or a digital reader.
Adjust one thing at a time
If alkalinity is out, fix that before obsessing over pH. If sanitiser is low, dose it and give the water time to circulate. For pH fixes, use small doses and retest after the product has had time to mix.
This is where the test kit links back to the rest of the maintenance routine. A strip tells you the problem; it does not replace knowing how the water behaves. For dosing detail, our how to lower pH in a hot tub guide is the better place to go once the kit shows a high reading.
The CDC’s public-pool guidance is much stricter than a domestic garden routine, but it reinforces the same point: pH and disinfectant residual are the readings that matter before people use warm shared water.
What to buy with your test kit
A test kit is only useful if you can act on the results. You do not need a shed full of chemical tubs, but there are a few things worth having from day one.
The basic chemical shelf
For a chlorine or bromine hot tub, I would keep:
- Sanitiser: chlorine granules or bromine tablets, usually £15-£30 depending on size and brand.
- pH reducer: often sold as pH Minus, about £8-£12.
- pH increaser: useful less often, about £8-£12.
- Alkalinity increaser: about £10-£15 and worth owning if your pH wanders.
- Non-chlorine shock or chlorine shock: about £12-£25, depending on system.
You can buy these from Amazon UK, Pool & Spa Centre, Hot Tub Barn and many local spa dealers. I would rather buy known brands such as Clearwater, Fi-Clor, Blue Horizons, AquaSPArkle or Bayrol than the cheapest anonymous tub with vague dosing instructions. If you are starting from scratch, our hot tub chemicals for beginners guide explains the dosing kit that sits beside the test strips.
A notebook or phone note
This sounds fussy, but record your readings for the first month. Write down date, pH, sanitiser, alkalinity, what you added and how the water looked the next day. After a few weeks you will know how your tub behaves.
For example, if your 1,000-litre inflatable tub always drops sanitiser hard after four people use it, you stop being surprised. If your hard-water area pushes pH up every refill, you can plan around it.
Spare filters and a rinse routine
Testing will not save water with a filthy filter. Keep at least one spare filter so you can swap and clean properly. A pair of inflatable spa cartridges might be £12-£25, while hard-shell filters often sit around £25-£60 each.
If your strip says sanitiser is fine but the water looks dull, the filter may be part of the problem. Our how to clean hot tub filters guide is worth pairing with any water-testing routine.
Testing routine for UK hot tub owners
The routine does not need to be complicated. It does need to be consistent.
Before every soak
Test sanitiser and pH before people get in. This matters more after rain, heavy use, a fresh refill or a few days with the cover on. If sanitiser is low, do not shrug and get in anyway.
For a family tub used at weekends, a 50-strip tub lasts longer than you think. Even testing three or four times a week, you are talking about roughly £1 a week in strips. That is cheap compared with draining, refilling and reheating a neglected tub.
Weekly
Check alkalinity and, if your kit supports it, hardness. Clean or rinse the filter. Look at the water with the jets off. Clear water is not proof of safe water, but dull or foamy water is a useful warning.
If you shock weekly, test before and after the shock has cleared according to your chemical instructions. Do not test pH while sanitiser is sky-high and then start adjusting based on a bad reading.
After a refill
Test source water, balance alkalinity, then pH, then sanitiser. This order saves a lot of chasing. Fresh UK mains water can vary a lot by region, so do not assume your friend’s dosing routine will work at your house.
If you are filling a new tub, also check the volume in litres. Chemical dosing is usually based on water volume, and guessing between 800 litres and 1,200 litres is enough to overshoot.
After parties or heavy use
Test as soon as the tub has circulated. Four adults, drinks, sun cream and a long evening can flatten sanitiser. If the strip says sanitiser has fallen, treat it before putting the cover back on for days.
This is where cheap strips earn their keep. They are not perfect, but they remove the worst habit in hot tub ownership: assuming yesterday’s water is still fine today.
Frequently Asked Questions
What is the best hot tub water test kit for most UK owners? For most UK owners, a good 3-way or 4-way strip kit from AquaChek, Blue Horizons or Clearwater is the best first buy. Expect to pay about £9-£16 for 50 strips.
Are digital hot tub testers better than strips? Digital testers can be easier to read, but they are not always better value. A proper photometer can cost about £186, while cheap pH pens miss sanitiser and alkalinity.
How often should I test hot tub water? Test sanitiser and pH before each soak, then check alkalinity weekly and after refills. Test more often after heavy use, rain, parties or chemical changes.
Can I use swimming pool test strips in a hot tub? Sometimes, but only if they measure the right sanitiser and range for your system. Hot tubs run warmer and smaller than pools, so use spa-compatible strips where possible.
Do bromine hot tubs need different test strips? Yes, use strips that include a bromine scale or a bromine-specific kit. Do not rely on chlorine-only strips unless the label clearly explains the bromine reading.
Should I test pH or alkalinity first? Check both, but fix alkalinity first if it is out of range. Alkalinity buffers pH, so pH adjustments can become frustrating if alkalinity is wrong.