Flocculant vs clarifier
Updated: 21 October 2026
The bottle says clarifier, the next one says flocculant, and a third says shock. Flocculant vs clarifier is a real fork, and shock is a third job. A clarifier helps a filter hold fine dirt. A drop floc clumps particles so they sink for a waste vacuum, or so a sand bed can catch them. Shock oxidises. The [Flocculant pool comparison](/hub/pool-care/flocculant-pool) is the product table. A qualifying amazon.co.uk purchase can earn us a commission at no extra cost to you. We did not lab-test clarity.
The bottle says clarifier, the next one says flocculant, and a third says shock. Flocculant vs clarifier is a real fork, and shock is a third job. A clarifier helps a filter hold fine dirt.
The bottle says clarifier, the next one says flocculant, and a third says shock. Flocculant vs clarifier is a real fork, and shock is a third job. A clarifier helps a filter hold fine dirt. A drop floc clumps particles so they sink for a waste vacuum, or so a sand bed can catch them. Shock oxidises. The Flocculant pool comparison is the product table. A qualifying amazon.co.uk purchase can earn us a commission at no extra cost to you. We did not lab-test clarity.
Our top picks
| Badge | Product | Job on the label | Filter | Dose point | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Bayrol Bayrol Superflock Plus, 1 kg | Filter-aid floc | Sand or glass | In the skimmer | 9.2 | about £22.02 | View offer |
| Alternative |  Blue Horizons Blue Horizons granular floc, 2 kg | Drop floc | Sand only | Vacuum to waste | 9.0 | about £18.91 | View offer |
| Alternative |  Not stated Swimming pool clarifier cubes | Title says clarifier | Not stated | Pump basket in reviews | 8.8 | about £16.99 | View offer |
On this page
Three jobs, three words
ManoMano's UK guide says clarifiers do not clump debris the way flocculants do. Bayrol's Superflock page says a floc aggregates particles so sand or glass can hold them, and it is not for cartridge filters. Superflock itself remains a floc.
Shock is for live algae. A shock clarifier is still a shock. HTH Clarishock, ASIN B00HH9WADW, was removed because the job is oxidation. If the pool is green, shock and brush first. Test before a bottle goes in.
What the titles in this comparison actually are
Blue Horizons is a drop floc: sand only, then vacuum to waste. The word clarifier is not that job. HTH rapidfloc is 3 litres at pH 6.9–7.8 with no filter named. One UK reviewer vacuumed it to waste. Treat the bottle as silent until you read it.
Superflock Plus and HTH Regularfloc are skimmer aids, then a backwash, not a powder you hoover off the floor. The about £22.02 Superflock listing is the best value of that name. Jolly Gel is a pump-basket floc, not a slow clarifier for a cartridge. Cubes Swimming Pool Clarifier, about £16.99, names no brand, and UK reviews call it Jolly Gel. Do not assume every clarifier on amazon.co.uk is a mild liquid.
The filter decides the word
A sand or glass filter can take a flocculant that needs a backwash or a waste line. A cartridge usually wants a slower clarifier, if it wants anything, because there is no waste setting for a sunk layer. Bayrol will not put Superflock Plus on a cartridge filter. Intex says flocculant clogs cartridge pumps. Magnum says most flocs can affect a cartridge warranty unless water can go to waste.
The unnamed cube listing says clarifier and, in UK reviews, behaves like a gel floc. One reviewer said fibre-ball filters stopped until they were washed. The sand-filter page maps which listings name sand. The buying guide is the wider decision once the word is clear. Do not stack a clarifier and a drop floc in the same hour.
When neither bottle is the next step
If free chlorine is low or the pH is high, fix that and run the pump. A stopped pump will cloud a pool that was fine on Sunday, and no cube repairs a pump that is off. If you can already see the deep-end floor, you may not need a floc this week.
Green water is shock first. Floc does not kill algae. After the algae is dead, a drop floc can sink the debris if you have sand and a waste line. Clarifier on a shock tub is not a mild third option. When a floc really is the next step, the how to use pool flocculant page keeps the clocks separate.
Common questions
What is the difference in one sentence?
A clarifier helps the filter hold fine dirt, a flocculant clumps that dirt so sand can catch it or so you can vacuum it to waste, and shock oxidises. They are not three strengths of the same liquid. The filter you own decides which of the first two is even possible. A cartridge pool and a sand pool should not share one bottle.
Will a clarifier sink dirt to the floor?
A true clarifier is not supposed to. ManoMano's guide says clarifiers do not clump debris the way flocculants do. A drop floc such as Blue Horizons settles debris for a waste vacuum. Some titles say clarifier on gel cubes whose reviewers describe a floc. If the dose point is the pump basket and a backwash, you have a floc with a soft title.
Can I use flocculant in a cartridge pool?
Not the flocculants in this comparison. Superflock Plus, Jolly Gel and Blue Horizons are sand or glass products, and the maker pages exclude cartridges. Intex and Magnum warn that floc clogs cartridge media, and Magnum mentions the warranty. A cube titled clarifier is not automatically a liquid for cartridges.
Is a shock clarifier a floc?
No. HTH Clarishock was taken out of this comparison because it is a shock clarifier, ASIN B00HH9WADW. Shock raises chlorine to oxidise. A floc clumps particles. A clarifier helps a filter. Putting shock in because the title says clarifier doses oxidiser, not a filter aid.
Why does a cube listing say clarifier?
Because the title is Cubes Swimming Pool Clarifier, and the page never names a brand. UK reviews call the contents Jolly Gel and describe flocking, with the cube in the pump basket. The named Jolly Gel listing does not need that guess. If clarifier is the only reason you chose those cubes for a cartridge pool, put them back.
Do I floc a green pool first?
No. Shock and brush first, with chlorine and pH in the range on the shock label. Floc does not kill algae. After the algae is dead, a drop floc can sink the debris if you have a sand filter and a waste line. A clarifier will not do that sink. If you cannot see the floor, stay out.
Can I use both a clarifier and a flocculant?
Not together, and not on the same afternoon. A clarifier is a slower filter aid. A drop floc is a mess you must remove. Chemicals for Pools notes that too much floc sticks media. Bayrol notes that too much flocculant clouds the water. Finish one sequence, backwash or vacuum, and retest before a second bottle.
Related pages
Sources
Public UK and maker sources used for this page in October 2026. Shelf prices and star lines are the amazon.co.uk figures for these nine listings, dated 19 October 2026.
- HSE: Swimming pools (retrieved 21 October 2026)
- HSE: GB CLP (retrieved 21 October 2026)
- PWTAG: Cloudy water technical note (retrieved 21 October 2026)
- PWTAG: Code of Practice (retrieved 21 October 2026)
- East Lindsey: Small swimming pools guidance (retrieved 21 October 2026)
- Bayrol: Superflock Plus data sheet (retrieved 21 October 2026)
- Bayrol: Quickflock liquid (retrieved 21 October 2026)
- Jolly Gel, Mineral Supplies International (retrieved 21 October 2026)