Chlorine tablets buying guide
Updated: 16.10.2026
You have an outdoor pool or a hot tub, and the search still says 5 kg chlorine tablets. On amazon.co.uk that line covers three different buys: a multifunction tablet, a stabilised tablet, and a small kit whose title says multifunction without listing the ingredients. This chlorine tablets buying guide is the order to sort them. Choose the chemistry, then the tablet size, then a pack whose title and weight agree. Star lines and prices for the seven kept listings are on the [chlorine tablets for pools](/hub/pool-care/chlorine-tablets-pool) comparison. The Products Compared editorial team wrote this from those amazon.co.uk listings and public UK retailer notes on 15 October 2026. It is not a lab test.
You have an outdoor pool or a hot tub, and the search still says 5 kg chlorine tablets.
You have an outdoor pool or a hot tub, and the search still says 5 kg chlorine tablets. On amazon.co.uk that line covers three different buys: a multifunction tablet, a stabilised tablet, and a small kit whose title says multifunction without listing the ingredients. This chlorine tablets buying guide is the order to sort them. Choose the chemistry, then the tablet size, then a pack whose title and weight agree. Star lines and prices for the seven kept listings are on the chlorine tablets for pools comparison. The Products Compared editorial team wrote this from those amazon.co.uk listings and public UK retailer notes on 15 October 2026. It is not a lab test.
Our top picks
| Badge | Product | Tablet type | Tablet size | Stated pack | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Deep Blue Deep Blue stabilised 200 g tablets | Stabilised chlorine, not multifunction | 200 g | Title 5 kg; weight and model 1 kg | 7.3 | about £31.49 | View offer |
 Relax Relax 5 kg multifunction tablets | Multifunction | 200 g (3 inch) | 5 kg, 25 tablets | 8.8 | about £26.99 | View offer | |
| Best value |  Deep Blue Deep Blue 5 kg 20 g multifunction tablets | Multifunction | 20 g | 5 kg; unit count says 1.0 count | 8.4 | about £21.98 | View offer |
On this page
Three different tablets hide under one search
Stabilised chlorine, in the split used by Swimming Pool Chemicals, is the tablet you put in a skimmer or a floater. Multifunction tablets are the same idea plus a flocculant and an algaecide. That shop’s prices are not amazon.co.uk prices.
Relax states stabilised chlorine, a clarifier and an algaecide, and it is the only listing that names trichloroisocyanuric acid. Both Deep Blue multifunction tubs state the same three jobs without naming the chlorine compound. ChlorineXpress and the Deep Blue stabilised listing name cyanuric acid and not the chlorine compound. Bulla’s title says multifunction, and the bullets do not list those ingredients. SINPY states no chemistry. The two chemistries set against each other are on multifunction vs stabilised chlorine tablets.
200 g, 20 g, or a 1 inch kit
A 200 g tablet is the slow puck for a pool that already has a feeder. Relax also calls that size 3 inch. Deep Blue’s 20 g multifunction tablets are the small ones, and the written reviews in this set come from hot-tub users. Bulla’s kit is 1 inch tablets sold with a floater.
Happy Hot Tubs sells large 200 g multifunction tablets and still tells hot-tub owners not to use that size, because of the puck and stabiliser in a small covered tub. That is the retailer’s warning, not a test of these ASINs. Both kits print seven tablets per 2,500 gallons a week, and neither says which gallon. A floater in the same box is a different purchase from a season’s tub, which is what chlorine tablets for a small pool is for.
A 5 kg title is not always a 5 kg tub
Four tubs agree on 5 kg, so they can be compared per kilo: Deep Blue’s 20 g tub at about £21.98, ChlorineXpress at about £24.99, Relax at about £26.99, and Deep Blue’s 200 g multifunction tub at about £28.23.
The Deep Blue stabilised listing cannot. The title says 5 kg at about £31.49, while the unit count and the item weight say 1 kg and the model is DBPCLTAB2002-1X1kg. The kits fail the same test at a smaller scale. SINPY is about £12.99, with 100 g, 220 g and 180 g on the same page. Bulla is about £16.99, with 1 lb, 500 g and 670 g. Once the kilograms match, the dose is the job of how to use chlorine tablets in a pool.
Stabilised means cyanuric acid stays in the water
Stabilised does not mean a stronger tablet. It means cyanuric acid is already in the puck and stays in the water. UK Pool Store’s sheet puts that retailer’s ideal at about 30–50 ppm. The way down is dilution. Do not buy a separate stabiliser on top of a tub that is already stabilised, unless that tub’s own label tells you to. None of these listings does.
The Health and Safety Executive points operators of managed pools to PWTAG. That standard is not a garden-pool dose. ChlorineXpress has no star line and still names cyanuric acid. The Deep Blue stabilised listing has the highest stars here and an unresolved kilogram. Read the chemistry and the weight before the stars.
Chemistry, then size, then the kilograms
If the bullets list stabilised chlorine, a clarifier and an algaecide, that is the multifunction buy. If you want to dose algaecide yourself, take a stabilised listing whose title and weight already agree. If the title says 5 kg and the weight says 1 kg, do not price it per kilo. A qualifying purchase can earn a commission at no extra cost to you.
Common questions
Should I buy multifunction or stabilised tablets for an outdoor pool?
Choose multifunction when the listing lists stabilised chlorine, a clarifier and an algaecide, and you will not buy three bottles. Choose stabilised chlorine when you want to dose algaecide and clarifier yourself. Bulla’s title says multifunction and the bullets do not list those ingredients. Relax is the only tub here that names trichloroisocyanuric acid.
Can I use a 200 g pool tablet in a hot tub?
Happy Hot Tubs sells large 200 g multifunction tablets and still tells hot-tub owners not to use that size, because the puck is large and stabiliser builds up in a small covered tub. That is a retailer’s warning, not a test of these ASINs. The small tablet in this capture is Deep Blue’s 20 g tub.
Why do two Deep Blue listings both say 200 g?
They are different products. The multifunction listing states stabilised chlorine, a clarifier and an algaecide. The stabilised listing tells you to dose algaecide and clarifier separately, and it names cyanuric acid. One is not a refill of the other. The stabilised listing also disagrees with itself about 1 kg and 5 kg.
The title says 5 kg and the weight says 1 kg. What do I buy?
Do not treat the Deep Blue stabilised listing as a settled 5 kg tub. The title says 5 kg at about £31.49. The unit count and the item weight say 1 kg, and the model is DBPCLTAB2002-1X1kg. For a 5 kg price per kilo, use a listing whose title and weight already agree, from about £21.98 to about £28.23 in this set.
Do I still add separate stabiliser if the tablet is already stabilised?
Not unless the label on the tub you opened tells you to. None of these listings does. Stabilised means cyanuric acid is already going into the water. UK Pool Store’s way down is dilution, and the sheet’s ideal is about 30–50 ppm, which is that retailer’s figure, not a garden-pool law.
Does a higher star score mean the chemistry is named?
No. ChlorineXpress has no star line in the raw file and still names cyanuric acid. The Deep Blue stabilised listing has the highest stars here and an unresolved pack weight. Relax is the only listing that names trichloroisocyanuric acid. That is a labelling fact, not a prize for the star line.
Related pages
Sources
Public UK sources listed in the research digest. Listing prices, stars, and review counts are from the amazon.co.uk capture dated 15 October 2026, not a live re-check.
- HSE — Swimming pool safety management (retrieved 15 October 2026)
- HSE SR9 — Safe use of pool biocides (retrieved 15 October 2026)
- HSE — Biocides regulations (retrieved 15 October 2026)
- HSE — GB CLP classification and labelling (retrieved 15 October 2026)
- PWTAG Code of Practice (retrieved 15 October 2026)
- PWTAG TN68 — Handling and storage of pool chemicals (retrieved 15 October 2026)
- UK Pool Store — What is cyanuric acid (retrieved 15 October 2026)
- Swimming Pool Chemicals — Chlorine tablets (retrieved 15 October 2026)