Clean, clear, well-balanced water is what makes a hot tub a joy to use — and it’s also what keeps your warranty valid. The good news: a simple routine of testing, balancing, and the occasional deep clean is all it takes. Here’s everything you need, from first fill to your everyday rhythm.
Balanced water comes down to five readings. Get these into range and your sanitiser works properly, the water feels good on the skin, and nothing damages your spa over time. Test with strips or a liquid kit, and always balance in this order: alkalinity first (it buffers everything else), then pH, then sanitiser.
| Reading | Target range | Why it matters |
|---|---|---|
| Bromine | 3 to 5 ppm | A primary sanitiser, gentle on skin and very stable in warm water. Often used as tablets in a dispenser. Test daily. |
| Free chlorine (alternative) | 3 to 5 ppm | An alternative sanitiser, fast-acting and widely used. Use granular, not tablets. Test daily. |
| pH | 7.2 to 7.8 (aim for 7.4 to 7.6) | Too low corrodes equipment and stings eyes. Too high clouds the water and weakens sanitiser. Check daily. |
| Total alkalinity | 80 to 120 ppm | The buffer that keeps pH stable. Set this first, before adjusting pH. |
| Calcium hardness | 150 to 250 ppm | Too soft and the water turns foamy and corrosive. Too hard and you get scale. Check monthly. |
These are general guidelines aligned with UK industry (BISHTA) advice. Dosing varies by product, so always follow the directions on your chosen chemical brand, and any specific guidance for your hot tub model.
Slow-dissolving chlorine tablets (trichlor), used in a floating dispenser or skimmer, sit against the acrylic and release highly concentrated, acidic chlorine that bleaches and damages the shell. This will void your warranty. If you sanitise with chlorine, use granular chlorine added directly to the running water instead.
Bromine is different from chlorine. It’s the one sanitiser made in spa-safe tablets, so using bromine tablets in a dispenser is a perfectly good way to look after your hot tub. As with any floating dispenser, set a low feed rate, keep the float moving, and don’t leave it parked against the shell or sealed under a closed cover, so the sanitiser can’t over-concentrate in one spot.
Stay on top of these and problems rarely start. The whole routine takes a few minutes a couple of times a week.
Rule of thumb for a water change: divide your tub volume in litres by 3, then by the number of people who use it each day, to estimate the days between changes. Most tubs land somewhere around every 8 to 12 weeks, sooner with heavy use.
Whether it’s your very first fill or a quarterly water change, the startup steps are the same.
Safety: always isolate the power before draining, cleaning, or working on your spa.
Usually low sanitiser, high pH or alkalinity, a dirty filter, or fine particles. Clean the filter, balance the chemistry, add a dose of shock, and run the filtration for 24 hours. A water clarifier helps bind very fine particles, and a metal sequestrant helps if your tap water is high in metals. If it keeps returning, flush the pipework to clear biofilm.
Foam comes from body oils, lotions, fake tan, and detergent left in swimwear, often made worse by old, over-used water. An anti-foam product is a quick fix for the moment, but the real cure is a deep clean and fresh water. Rinse off before getting in, and avoid washing swimwear in detergent.
Counter-intuitively, a strong smell usually means too little active sanitiser, not too much. It’s caused by chloramines, the spent by-products of sanitising. Shock the water and make sure free sanitiser is back in range. A musty or eggy smell points to bacteria and low sanitiser: raise the sanitiser, shock, and if it persists, drain, flush the lines, and refill.
The filter does the quiet work of keeping your water clear. Rinse it under a hose every week, give it an overnight soak in filter cleaner once a month (then rinse it thoroughly so no cleaner carries back into the tub), and replace it about once a year — or sooner if it loses its shape or won’t come clean.
Your hot tub is run by its control system, and the topside panel is your window into it: setting the temperature, filtration cycles, and cleaning modes. Most of our tubs use a Balboa, Gecko or SpaNet control pack, and our Wellis models have their own guide — the control brand is usually printed on the topside panel. Download the one that matches your tub below.
Not sure which control system your tub has, or need the manual for your exact model? Get in touch and we’ll send the right one over.
For a step-by-step walkthrough of everything on this page, we recommend the “Hot Tub Water Chemistry” video series by Swim University: testing, balancing, shocking, clearing cloudy water, and more. The chemistry is universal — just remember the UK adjustments above (granular chlorine rather than tablets, and the slightly higher sanitiser levels).
Watch the video seriesWater care should never be stressful. If anything looks off or you’re not sure what to add, get in touch and we’ll talk you through it. You can also read the full warranty terms for what your cover includes.