The best pool flocculants, compared.
Top pick: Bayrol Superflock Plus cartridge, 1 kg – Highest score in the set: 4.7 from 318 reviews at about £47.78. The title says 1 kg and the same page also prints 29.57 ml. Best value: Bayrol Superflock Plus, 1 kg – About £22.02 for a 1 kg skimmer cartridge, 4.6 from 4,576 reviews. Bayrol's sheet limits it to sand or glass, up to 50 m³. Updated October 2026.
A pool flocculant sticks fine particles together so a sand or glass filter can catch them, or so they sink and you can vacuum them to waste. Use it for cloudy water once chlorine and pH are already in range. It does not replace shock on a green pool. If you cannot see the deep-end floor, do not swim. A gel cube goes in the pump basket on sand, glass or zeolite. A weekly skimmer cartridge is for sand or glass, then a backwash. Cartridge, diatomaceous-earth and fibre-ball filters are the wrong match for those jobs. The same page also prints a unit count of 29.57 ml. The [pool flocculant buying guide](/hub/pool-care/flocculant-pool/sub/flocculant-pool-buying-guide) matches form to filter before you order. Public pools dose coagulant continuously under, and domestic pools sit outside that code. PWTAG's cloudy-water note uses 0.5 as a guideline and says you should see the deepest bottom from the side. Cloudiness is often low chlorine, a stopped pump, or high pH. East says keep a small pool closed if the deep end is not clearly visible.
A pool flocculant sticks fine particles together so a sand or glass filter can catch them, or so they sink and you can vacuum them to waste. Use it for cloudy water once chlorine and pH are already in range.
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Personal buying guide
Question 1 of 2
Where does the dose have to go?
This Bayrol Superflock Plus listing shows 4.7 from 318 amazon.co.uk reviews and a shelf price of about £47.78, the highest score in the set and also the highest price. The title and the item weight say 1 kg, while the same page prints a unit count of 29.57 ml, and the model number printed is localization_B008AC78GE. The listing does not name a filter. It is ranked under pool and hot tub filter cartridges, and a benefit line says it controls cloudy water. The first 50 written review blocks are marked Germany, not the United Kingdom. They describe a pouch in the skimmer and a backwash, and some report torn pouches or no improvement. The other Superflock Plus ASIN was about £22.02 for a 1 kg title. Buy this one only if the pack you are shown matches the 1 kg cartridge you expect.
Pros
Cons
Best for: A buyer who has confirmed this pouch is the 1 kg Superflock Plus cartridge.
Less suitable: Anyone who can buy the £22.02 Superflock Plus listing, or a cartridge-filter hot tub.
Specifications
Common questions
What size is the pack?
The title and the item weight say 1 kg. The unit count on the same page says 29.57 millilitres. Both figures are printed. The model number is localization_B008AC78GE.
Does the listing name a filter?
No. Filter type, mixing and pool safety are unanswered on the page. A benefit line says it controls cloudy water. It is ranked under pool and hot tub filter cartridges.
Where were the written reviews from?
The first 50 review blocks are marked Germany, not the United Kingdom. They describe putting a pouch in the skimmer and backwashing. Some report torn pouches or no improvement.
Bayrol Superflock Plus at about £22.02 is a 1 kg cartridge the listing says to place in the skimmer, rated 4.6 from 4,576 amazon.co.uk reviews. Bayrol's data sheet, which is fuller than this listing, limits Superflock Plus to sand or glass, one cartridge up to 50 m³, and says it is not for cartridge filters. The amazon bullet mentions lanthanum, phosphates, iron and copper. The data sheet names lanthanum(III) chloride hydrate plus aluminium sulfate, so the bullet is a shorthand. The same listing also prints batteries required and an air power source, which read as listing noise rather than features of a skimmer sock. A second Superflock Plus ASIN was about £47.78 for a title that also says 1 kg. This listing is the weekly skimmer cartridge at the lower of those two shelf prices, and it still needs a backwash afterwards.
Pros
Cons
Best for: A weekly sand or glass filter where a skimmer cartridge and a backwash are the routine.
Less suitable: Cartridge or DE filters, and anyone comparing it with the £47.78 Superflock Plus listing without checking the pack.
Specifications
Common questions
Where does the listing say to put it?
The bullet says this flocculent cartridge is placed in the skimmer. It does not say whether that suits every skimmer.
What does the listing claim about metals?
A bullet says the product removes phosphates and is also suitable for removal of iron and copper. Bayrol's data sheet names lanthanum(III) chloride hydrate plus aluminium sulfate. The bullet is a shorthand, not a measured result.
Are the battery lines real features?
The listing also prints batteries required and an air power source. Those lines are not explained. Treat them as listing noise, not as confirmed features.
Jolly Gel, from Mineral Supplies International, is listed here as two boxes, eight cubes, at about £24.99, rated 4.6 from 136 amazon.co.uk reviews. The maker puts one cube in the pump basket, not the skimmer, on sand, glass or zeolite, and not on a cartridge or diatomaceous-earth filter. UK reviewers describe cutting a cube so it fits. One says a whole block does not fit a basic filter. The listing says it removes phosphates and works in a few hours. One UK reviewer with an indoor pool still measured about 3,000 on a phosphate test while using the cubes about every two weeks, and also reported fine white dust on the floor. The maker prints both up to 12,500 gallons and 20–60 m³, which are not the same volume. Package weight on this listing is 570 g.
Pros
Cons
Best for: A sand, glass or zeolite filter where you can put a cut cube in the pump basket.
Less suitable: Cartridge or diatomaceous-earth filters, and a buyer treating the phosphate bullet as a measured result.
Specifications
Common questions
What does the listing claim?
The listing says it removes phosphates, improves water clarity and works in a few hours. Saltwater use, algae removal and how long it lasts are questions with no answer on the page. One UK phosphate test stayed about 3,000 during use.
Where do UK reviewers put the cube?
They describe cutting a cube and putting it in the pump or filter basket. One says a whole block does not fit a basic filter. The maker's page says the pump basket, not the skimmer.
Did a reviewer check the phosphate claim?
One UK reviewer with an indoor pool reported a phosphate test still about 3,000 while using the cubes about every two weeks, and also reported fine white dust on the floor.
HTH Regularfloc is a pack of 10 cartridges at about £22.84, rated 4.6 from 61 amazon.co.uk reviews, and the listing names a sand filter. The item weight is 1.4 kg. The page asks whether it suits every sand filter and does not answer. Saltwater use and how often to replace a cartridge are also unanswered. One review, not from the UK, says it is not for a cartridge filter. Of seven review blocks, one is marked United Kingdom and calls them good quality flock tablets. Ten cartridges is a longer shelf supply than a single sock if your skimmer accepts this format, though the listing does not print a pool-volume limit. You still backwash a sand filter after use. These are a filter aid, not a vacuum-to-waste floc.
Pros
Cons
Best for: A sand-filter pool whose skimmer takes a weekly floc cartridge.
Less suitable: Cartridge filters, and a one-off drop where you need to vacuum the floor to waste.
Specifications
Common questions
What is in the pack?
The listing says 10 Regularfloc cartridges to improve fine filtration of swimming pools with a sand filter. The item weight is 1.4 kg.
Will it suit every sand filter?
The page asks that and does not answer it. Saltwater use and how often to replace a cartridge are also unanswered. One review, not from the UK, says it is not for a cartridge filter.
How many UK reviews are in the sample?
One of seven review blocks is marked United Kingdom and calls them good quality flock tablets. The rating line is 4.6 from 61 reviews.
Blue Horizons granular floc is a drop treatment for a sand-filter pool. You pre-dissolve at most 100 g in 10 litres of clean warm water, add it on recirculate, then vacuum the settled debris to waste. Across 61 amazon.co.uk reviews it sits at 4.5, and UK reviewers describe dead algae sinking so it can be hoovered out. The listing prints sand filters only, so a cartridge or fibre-ball set-up is outside what this listing allows. One reviewer said the tub looked closer to 1.5 kg than the 2 kg title, and another said it had not worked yet. The shelf price on 19 October 2026 was about £18.91, with an item weight of 2.1 kg. Saltwater use, storage and surface safety are questions on the page with no answer. The granules do not clear the floor by themselves. You still need a waste setting and a vacuum.
Pros
Cons
Best for: A sand-filter pool where you can vacuum settled debris to waste.
Less suitable: Cartridge or fibre-ball filters, or a pack you cannot check against the 2 kg title.
Specifications
Common questions
Which filters does the listing allow?
The listing says this granular floc should only be used in pools with sand filters. Saltwater use, storage and surface safety are questions on the page with no answer.
How is it dosed on the listing?
Pre-dissolve at a maximum of 100 g per 10 litres of clean warm water, stir, and add evenly with filtration in recirculation mode. Settled particles should be vacuumed to waste.
What do UK reviews repeat?
Reviewers describe dead algae sinking so it can be hoovered to waste. One says the tub was about 1.5 kg rather than 2 kg, and one said it had not worked yet.
This listing is titled Cubes Swimming Pool Clarifier, costs about £16.99, and does not name a brand. The package weight is 300 g, the cube count is not stated, and the rating is 4.4 from 132 amazon.co.uk reviews. UK reviews call the gel Jolly Gel and describe flocking a pool, which is reviewer language rather than a brand printed in the title. They say to put the cube in the pump basket, not the skimmer, or it may not dissolve. One reviewer says fibre-ball filters stopped working until they were washed. Another cuts the cubes down for a hot tub, and the listing does not answer whether hot tubs or algae are in scope. If you need a named maker and an eight-cube count, the Mineralsi listing states those facts. This cheaper title is only a match when the gel you receive is the cube you already know how to dose.
Pros
Cons
Best for: A sand-filter owner who already recognises this gel and doses it in the pump basket.
Less suitable: Fibre-ball filters, and anyone who needs the brand printed before they order.
Specifications
Common questions
Is the brand named?
No. The title is Cubes Swimming Pool Clarifier. UK reviews call the gel Jolly Gel and describe flocking a pool. That is reviewer language, not a brand in the title.
What filter problems appear in UK reviews?
One reviewer says fibre-ball filters stopped working until they were washed. Others say put the cube in the pump basket, not the skimmer, or it may not dissolve.
Are hot tubs and algae answered on the listing?
No. Those questions, and whether it suits all pool types, have no answer on the page. One reviewer cuts the cubes down for a hot tub.
HTH rapidfloc is a 3 litre liquid at about £23.32, rated 4.4 from 83 amazon.co.uk reviews. The listing says it is effective at pH 6.9–7.8 and that the bottle is graduated, which helps if you are measuring a partial dose. It does not name a filter type, a millilitre dose, or whether salt water is allowed. A benefit line says it improves filtration efficiency and water transparency, which is a listing claim rather than a measured result. One UK reviewer reported clear water after vacuuming to waste, and said not to put the pool back on filtration until the product had finished working. Most other written reviews in the sample are not from the United Kingdom, so that single UK account is the local written evidence. Treat it as a drop-style liquid only when the label in the box matches that vacuum-to-waste sequence.
Pros
Cons
Best for: A pool whose label in the box tells you to vacuum this liquid to waste.
Less suitable: A cartridge filter, or anyone who needs a printed filter type before buying.
Specifications
Common questions
Does the listing name a filter?
No. Whether it suits every filter, salt water, or children are questions on the page with no answer. A benefit line says it improves filtration efficiency and water transparency.
What pH does the listing print?
The listing says it is effective for pH 6.9 to 7.8, and that the bottle is graduated.
What does the UK review say about use?
One UK reviewer reported clear water after vacuuming to waste, and said not to return the pool to filtration until the product had finished working. Most other written reviews in the sample are not from the United Kingdom.
Bayrol Quickflock Super is a 1 litre liquid at about £20.50, with 4.3 from 1,586 amazon.co.uk reviews. The title names a sand filter, and the listing says to add 100–200 ml slowly over the skimmer with the pump running, circulate for 15 minutes, then let filtration catch the fine dirt and backwash if needed. That sequence is not Bayrol's separate Quickflock liquid page, which doses upstream of the filter and says not to pour that liquid into the pool. Several UK reviews say the bottle arrived with no English instructions. One reviewer said it clogged the filter. Another, with an 8 m by 4 m sand-filter pool, could not see the floor and reported clearer water after a few days. The review count does not replace a readable English label on the bottle you receive.
Pros
Cons
Best for: A sand-filter pool if the bottle in your hand has English directions you can follow.
Less suitable: A cartridge filter, or a buyer who needs the label language confirmed before it arrives.
Specifications
Common questions
How does the listing say to add it?
Add 100 to 200 ml slowly over the skimmer with the circulation pump running, run the pump for 15 minutes, then let filtration run so fine dirt sticks in the filter. Backwash and repeat if needed.
Which pool types are confirmed?
The title names a sand filter. Whether it suits all pool types, how often to use it, and whether to pre-mix are questions without answers on the page.
What do UK reviews complain about?
Several UK reviews say the bottle had no English instructions. One says it clogged the filter. Another UK reviewer reported clearer water after a few days on an 8 m by 4 m sand-filter pool.
Nortembio FLOC-0K24 is the cheapest listing here at about £11.95, titled as an eight-week treatment for small pools, plunge pools, hot tubs and spas. The rating is 3.9 from 789 amazon.co.uk reviews, the lowest stars in the set. The unit count says 240 g and the item weight says 340 g, so the pack size is not settled on the page. The listing says particles are easier for the filter to capture and also that they settle, which are two different jobs. A UK reviewer said a hot tub was left with floating slime, and other reviews describe a gel-like mass, a missing measuring scoop, or no change. Country of origin on the listing is Spain, and no chemical name is printed. A seller line calls the formula 100 percent natural, which is a seller sentence rather than a confirmed composition. Keep it to the small volume in the title.
Pros
Cons
Best for: A small pool or spa only if you accept the mixed listing lines and the 3.9 rating.
Less suitable: A full-size garden pool with a sand filter that needs a named dose and a waste line.
Specifications
Common questions
Who is it titled for?
The title names small swimming pools, plunge pools, hot tubs and spas, and says one treatment is for up to eight weeks. Country of origin on the listing is Spain.
Do the lines say it sinks or gets filtered?
Both. They say particles are easier for filtration to capture, and that they settle to the bottom. A 100 percent natural formula is a seller sentence. No chemical name is printed.
What went wrong in reviews?
A UK reviewer said a hot tub was left with floating slime. Other reviews describe a gel-like mass, a missing measuring scoop, or no change. The rating is 3.9 from 789.
Nine amazon.co.uk listings were compared from shelf prices and review lines dated 19 October 2026, plus the public sources below. There was no laboratory clarity test. A star line stays the amazon.co.uk figure. A written review marked outside the United Kingdom is not treated as British experience. The five weights below sum to 100. Awards follow the display scores: the highest score is the top pick, and the lower-priced Superflock Plus listing is the best value.
Filter match
25%Whether the listing or the maker's sheet names a filter this product can use. Sand or glass with a waste line can take a drop floc or a skimmer cartridge. Cartridge, diatomaceous-earth and fibre-ball filters are the wrong match for Jolly Gel and for sand-only granules.
Job
20%Whether the product is a weekly skimmer cartridge, an overnight drop you vacuum to waste, a pump-basket gel, or a small-pool powder. A weekly sock is not scored as a drop floc. Green water still starts with shock and brushing.
Dose point
20%Whether the label in your hand, or the maker's sheet where the listing is thin, says where the dose goes. Jolly Gel is the pump basket. Superflock Plus is the skimmer. Blue Horizons granules are pre-dissolved, then vacuumed to waste.
Pack and label
20%Whether the pack size is one figure, and whether UK reviews report English instructions. Two weights on one page, or a model number that is only a localisation string, are a deduction. A phosphate bullet is not treated as a measured result.
Review evidence
15%The amazon.co.uk star line and the written reviews that were read, with UK text ahead of reviews marked in another country. A large count does not replace a readable English label. The lowest stars in the set stay the lowest.
Match the form to the filter, then to the job, then to the dose point printed on the label you will actually hold. Price and stars come after those three. The notes below follow that order for these nine amazon.co.uk listings. None of the scores is a clarity test in a lab.
A pool flocculant sticks fine particles together so a sand or glass filter can catch them, or so they sink for vacuuming to waste. UK garden pools are hand-dosed. Public pools dose coagulant continuously under PWTAG, and domestic pools sit outside that code. You use a flocculant for cloudy water once chlorine and pH are already in range, not instead of shock and brushing on a green pool.
Flocculant is for cloudy water once chlorine and pH are already in range. A green pool still starts with shock and brushing. PWTAG's cloudy-water note treats low chlorine, a stopped pump and high pH as common causes. If you cannot see the deep-end floor, do not swim.
Jolly Gel goes in the pump basket, not the skimmer. Blue Horizons granules are sand filters only. A UK review of the unnamed cube listing says fibre-ball filters stopped until they were washed. Cartridge and diatomaceous-earth filters are outside the Jolly Gel maker's page.
Blue Horizons says vacuum settled debris to waste. Sending that floc back through the filter is the wrong valve position. Do not add a second dose before the first floc is removed. Bayrol says too much flocculant can cloud the water.
Sand or glass with a waste line can take a drop floc or a skimmer cartridge. Cartridge, diatomaceous-earth and fibre-ball filters are the wrong match for Jolly Gel and for sand-only granules. A UK review of the unnamed cube listing says fibre balls stopped filtering until they were washed. The job is the second split. A weekly sock, Superflock Plus or HTH Regularfloc, is not an overnight drop.
Read the dose point on the label in your hand. Jolly Gel is the pump basket, not the skimmer, and the maker's pH band is 7.2–7.6. Superflock Plus is the skimmer after backwash, pH 7.0–7.4 on the data sheet, one cartridge up to 50 m³. Quickflock Super's amazon.co.uk lines, 100–200 ml over the skimmer, are not Bayrol's Quickflock liquid page, which doses upstream of the filter and says not to pour that liquid into the pool. Pack size has to be one figure.
Three typical situations, each with a recommendation from this comparison.
You backwash a sand or glass filter and you want a skimmer cartridge, not an overnight drop. Bayrol Superflock Plus at about £22.02 is the 1 kg cartridge with 4.6 from 4,576 reviews. Bayrol's sheet limits it to sand or glass, one cartridge up to 50 m³.
The pool has a sand filter and a waste setting, and you can vacuum the floor after the floc settles. Blue Horizons granular floc, 2 kg, at about £18.91, is limited to sand filters. You pre-dissolve at most 100 g in 10 litres, then vacuum to waste.
You can put a cut cube in the pump basket, not the skimmer. Jolly Gel, eight cubes at about £24.99, is the named listing from Mineral Supplies International. It is not for a cartridge or diatomaceous-earth filter. A whole cube may not fit a basic basket.
The top pick is the Bayrol Superflock Plus cartridge at about £47.78. It has the highest score in this set, 4.7 from 318 amazon.co.uk reviews, and the title says 1 kg. The same page also prints 29.57 ml, the listing does not name a filter, and the first 50 written reviews are marked Germany, not the United Kingdom. The best value is Bayrol Superflock Plus, 1 kg, at about £22.02, with 4.6 from 4,576 reviews. Bayrol's sheet limits that cartridge to sand or glass, up to 50 m³, and it still needs a backwash. The other seven listings have no award. None of these scores is a lab test.
Bayrol Superflock Plus cartridge, 1 kg
Highest score in the set: 4.7 from 318 reviews at about £47.78. The title says 1 kg and the same page also prints 29.57 ml.
Bayrol Superflock Plus, 1 kg
About £22.02 for a 1 kg skimmer cartridge, 4.6 from 4,576 reviews. Bayrol's sheet limits it to sand or glass, up to 50 m³.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
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.
This page contains affiliate links to amazon.co.uk with the tag pcuk26-21. If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are the UK listing figures dated 19 October 2026. We did not lab-test these pool flocculants.
