Mini chlorine tablets are a simple sanitiser option for hot tubs and spa water. They dissolve slowly, making them useful for maintaining a steadier chlorine level between soaks when used in a suitable floating dispenser.
For most home hot tubs, mini chlorine tablets are chosen because they are smaller than swimming pool tablets and better suited to spa water volumes. They are best used for routine sanitation, while chlorine granules are often preferred when you need to raise the chlorine level more quickly.
Always test your spa water before and during tablet use so you can keep chlorine within the recommended range for your hot tub. The exact number of mini chlorine tablets needed depends on your tub size, water temperature, bather load and how often the cover stays closed.
If your hot tub is used frequently, test more often and top up sanitiser as needed. Good water balance helps mini chlorine tablets work properly, so keep pH in range and make sure your filtration and cleaning routine are consistent.
Slow-release stabilised chlorine for hot tubs and small pools. A 20 g trichlor (TCCA) tablet that holds 3-5 ppm free chlorine for up to a week per dose with cyanuric acid stabilisation.
Standard maintenance dose. Heavy bather load or hot weather can lift demand to 1.5 tablets per 4500 L per week.
Trichloroisocyanuric acid (TCCA) compressed into 20 g slow-release tablets. Each tablet contains approximately 90% available chlorine and built-in cyanuric acid stabilisation.
TCCA dissolves to release hypochlorous acid (the active sanitiser) and cyanuric acid (the stabiliser). The cyanuric acid binds reversibly to free chlorine and shields it from UV destruction, holding sanitiser through the day.
Unstabilised chlorine is destroyed within 2 hours of full sunlight. Stabilised TCCA tablets hold a full week of sanitisation in outdoor tubs and pools, slashing manual dosing and chlorine consumption.
3-5 ppm for hot tubs and 1-3 ppm for outdoor pools.
Up to 7 days in a 4500 L tub at standard temperature and bather load.
No. TCCA tablets are pre-stabilised with cyanuric acid.
50 tablets at 20 g each, about a year for a single 1500 L hot tub.
Yes, in a floating dispenser. Never drop tablets onto the vinyl shell.
Use only when the salt cell is offline; tablets are normally redundant in salt systems.
Trichloroisocyanuric acid (TCCA) at approximately 90% available chlorine.
A UV stabiliser that protects free chlorine from sun degradation. Required for outdoor use, undesirable indoors.
Yes, but switch to unstabilised chlorine if you do not need UV protection. Indoor CYA build-up wastes chlorine.
Increase tablet count or shock with a non-stabilised oxidiser; check filter is clean.
Combined chlorine high; shock with MPS and ventilate for 30 minutes.
TCCA is acidic; dose pH plus weekly to compensate.
TCCA is slow-release and acidic; SDIC is fast-acting and pH-neutral. Tablets for ongoing dosing, granules for top-ups and shocks.
TCCA is stabilised chlorine for outdoor use. Bromine is more stable at hot tub temperatures and gentler on bather skin.
How the three main hot tub sanitiser families compare for everyday use, hot water performance and running cost.
| What matters | Chlorine | Bromine | Chlorine dioxide |
|---|---|---|---|
| Best for | Fast, low-cost everyday sanitising | Hot tubs and spas that want a steadier, milder feel | Deep cleans, biofilm removal and problem water |
| Ideal level | 3 to 5 ppm free chlorine | 4 to 6 ppm total bromine | Used as a clean-up dose, not a daily residual |
| Performance in hot water | Burns off faster at spa temperatures | Stays effective in hot water | Used as a strong clean-up dose, often chosen for biofilm problems |
| pH sensitivity | Works best at pH 7.2 to 7.6 | Effective across a wider pH range | Largely unaffected by pH |
| Odour | Noticeable when chloramines build up | Milder than chlorine | Low odour at normal clean-up doses |
| Typical running cost | Lowest day to day | Slightly dearer than chlorine | More per dose, but only used occasionally |
| ClearSpa products | Stabilised chlorine granules and mini tablets | Bromine tablets 20g and bromine granules | Chlorine dioxide |