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How to winterise an above ground pool in the UK

Updated: 21 October 2026

A rigid frame pool and an inflatable look similar in August and fail in opposite ways in January. To winterise an above ground pool in the UK, split by structure first. Empty a rigid liner and the wall can collapse. Leave an inflatable standing and frost and wind do the damage. This page follows water level, pump, then cover. The chemical is one step. Rows and prices are on the [pool winteriser comparison](/hub/pool-care/pool-winteriser). Peter F. used the Relax sheet from Oasis and UK close-down notes, with amazon.co.uk listings from 19 October 2026. We did not winter a pool. A qualifying purchase can earn a commission at no extra cost to you.

A rigid frame pool and an inflatable look similar in August and fail in opposite ways in January. To winterise an above ground pool in the UK, split by structure first. Empty a rigid liner and the wall can collapse.

Our top picks

Kleen Pool Kleen Pool algaecide, 1 L

Best overall

Kleen Pool Kleen Pool algaecide, 1 L
7.5/10about £17.95
View offer
Blue Horizons Blue Horizons winter time algaecide, 5 L

Rank 2

Blue Horizons Blue Horizons winter time algaecide, 5 L
8.6/10about £29.20
View offer
AquaJoyer AquaJoyer winter closing kit

Alternative

AquaJoyer AquaJoyer winter closing kit
6.2/10about £29.06
View offer
On this page
  1. 1.Rigid pool or inflatable
  2. 2.Water level, pump, and pipes
  3. 3.Where the winteriser fits
  4. 4.Cover and ice

Rigid pool or inflatable

Relax's above-ground sheet, from Oasis, draws the line. Inflatables are emptied, dried, and stored. Most rigid-wall pools stay filled, because an empty liner and structure are damaged. A winteriser in an inflatable you are about to deflate is wasted. Dry the seams before the shed. The rest of this page is the rigid path. DP Pool Services names liner shrink and groundwater if you drain a shell that must stay supported.

Water level, pump, and pipes

Relax lowers a rigid pool to about 1 foot, about 30 cm, below the skimmer. Water Technics uses about 150–200 mm below the skimmer when you dose from a main drain. Your cover maker can override both. Mesh covers need a deeper drop because rain passes through. Once the chemical has circulated, disconnect the pump, filter, and any heater. Drain them, plug the openings, and store the pump where a freeze will not sit in the wet end. A housing left full is how a frame-pool pump cracks. A heater you cannot drain is the moment to stop. The dose order is how to winterise a swimming pool.
Kleen Pool Kleen Pool algaecide, 1 L

Testsieger

Kleen Pool Kleen Pool algaecide, 1 L
7.5/10about £17.95
View offer

Where the winteriser fits

A rigid pool that stays full still gets a winter product, after a shock and while the pump can spread it. Relax's 20 g per 1,000 litres is stabilised chlorine granules for that shock, not the winteriser dose. CATAGEN's without-filtration bullet is one listing, not this sequence. AquaJoyer, about £29.06, says two capsules up to 30,000 gallons. POOLHOUR, about £32.36, says up to 15,000 gallons and does not state a pod count. Neither prints a smaller dose, and the saved reviews are not from the United Kingdom. Which listing fits is best pool winteriser UK.

Cover and ice

After the pump is stored, tie down a winter debris cover. Relax says store the solar cover. One Blue Horizons review never tested the chemical because an above-ground cover blew off. Ice relief is a float, not a second chemical. Partly filled plastic bottles give the ice something to crush instead of the wall. A pool pillow does not replace the winteriser.

Common questions

Do I empty my frame pool?
No, if it is a rigid-wall pool with a liner meant to stay supported. Relax's sheet says most rigid pools stay filled because an empty liner and structure are damaged. Lower the water, on that sheet, to about 1 foot, about 30 cm, below the skimmer, unless your cover maker says otherwise. Draining it to the lawn is the failure to avoid. A small inflatable is the pool you do empty.
What about an inflatable?
Empty it, dry it, and store it. Relax treats inflatables as pools that are usually packed away, not left standing with a winter chemical and a cover. Frost in a wet seam, and wind on a tall ring, are the risks of leaving it up. There should be no water left to drop below a skimmer. A winteriser is the wrong product for a pool that will not stay full.
How far do I drop the water?
Relax uses about 1 foot, about 30 cm, below the skimmer on a rigid above-ground pool. Water Technics uses about 150–200 mm below the skimmer when dosing from a main drain. Mesh covers that let rain through need more drop so the pool does not overflow. If your cover says keep the normal level, follow the cover. A US skimmer-plate method is not the default here.
Do I still add a winteriser?
Yes, on a rigid pool you are leaving full, after cleaning and a shock, while the pump can still spread it. Relax's sheet puts a dedicated winter product after a shock of about 10 ppm. Their 20 g per 1,000 litres figure is that shock in stabilised chlorine granules, not the winteriser dose. An inflatable you are storing does not get this step.
What happens to the pump?
Disconnect it after the chemical has circulated, drain it, and store it off the pool. Drain the filter and the pipes and plug the openings. A pump left full of water on a frame pool can crack in a freeze even though the pool itself stays full. If a heater is plumbed in and you cannot find a drain, stop. Visible pipes still need emptying.
Solar cover or winter cover?
Store the solar cover. It is a summer heat cover, not a leaf cover for a British winter. Use a winter debris cover on the rigid pool and tie it down. A Blue Horizons review in this comparison lost the close because the above-ground cover blew off, so the chemical was never really in service. A loose cover lets rain and leaves undo the dose. Store the solar cover dry unless the maker says it can stay on.
Will a pool pillow replace the chemical?
No. A pillow or a partly filled bottle is ice relief. It gives the ice something to compress. It does not slow algae, and it was not kept as a product in this winteriser comparison. A rigid pool that stays full needs the winter chemical and some form of ice relief. An inflatable needs neither if it is dry in the shed.

Related pages

Pool winteriser buying guide

Pool winteriser

Best pool winteriser UK: which listing fits your pool

Copper free winter algaecide or a copper winteriser

How to winterise a swimming pool before hard frost

Sources

Public UK 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.

  1. HSE: Biocidal product authorisation (retrieved 21 October 2026)
  2. HSE: Managing health and safety in swimming pools (HSG179) (retrieved 21 October 2026)
  3. HSE: Swimming pools (retrieved 21 October 2026)
  4. PWTAG: Microbiological testing TN53 (retrieved 21 October 2026)
  5. Lo-Chlor: Winteriser algaecide tech sheet (retrieved 21 October 2026)
  6. Blue Horizons Ultimate winteriser sheet (retrieved 21 October 2026)
  7. Water Technics: Swimming pool winterising guide (retrieved 21 October 2026)
  8. HTH: Super Winterprotect 3 L (retrieved 21 October 2026)