Covering the water is the cheapest pool upgrade there is — but a “cover” is not a single product. A solar bubble cover, a winter cover with eyelets, an anchored safety cover, a slatted cover and a leaf net each solve something different and cannot stand in for one another. What follows is a comparison of covers: what each one does, how long it lasts, what destroys it and how to choose according to your priority.
If you are still weighing up whether to cover the water at all and what it will do to your energy and water consumption, start with Pool enclosures and solar covers; fixed sliding enclosures are covered in How to choose a pool enclosure. This article is about covers that lie on the water or just above it.
Five types of cover and what each one really does
The most common mistake when buying: someone buys a cheap bubble cover and expects safety from it, or invests in a safety cover and is surprised that the water is no warmer. Every type has one main function; the rest it handles only as a side effect.
| Cover type | Main function | Service life | Handling | Indicative price (4 × 8 m pool) |
|---|---|---|---|---|
| Solar bubble cover, 400 µm | Heating and reduced evaporation | 2–3 seasons | By hand or with a reel | €100–180 |
| Solar bubble cover, 500 µm | Heating, evaporation, higher durability | 3–5 seasons | Reel practically essential | €180–320 |
| Winter cover with eyelets and ropes | Protecting the water through winter | 4–8 seasons | Twice a year, by hand | €120–280 |
| Anchored safety cover | Preventing a person from falling through | 8–12 years | Tensioners, 10–20 minutes | €1,000–2,400 |
| Above-water slatted cover | Convenience + heating + partial safety | 10–15 years (slats 8–12) | Press a button, under 2 minutes | €2,400–4,400 |
| Below-water slatted cover | The same + hidden mechanism and looks | 10–15 years | Press a button, under 2 minutes | €4,400–8,000 |
| Leaf net | Catching coarse debris | 5–10 seasons | Tensioned with carabiners | €160–480 |
Prices are indicative for 2026 and apply to a rectangular 4 × 8 metre pool excluding installation. Unusual shapes and steps on the shorter side push the price up — easily by 20–30 % in the case of safety covers.
Solar bubble cover: why thickness in microns decides everything
A bubble cover is a film with air bubbles that floats directly on the water: it lets sunlight through while forming an insulating layer against evaporation — and evaporation is the main route by which a pool loses heat. The key parameter is thickness in microns (µm):
- 200 µm — the cheapest option, for above-ground pools. The bubbles start bursting during the first season. It lasts one, exceptionally two.
- 400 µm — a sensible standard for a family pool: stiff enough to roll up, still manageable by hand with two people. Service life 2–3 seasons.
- 500 µm — the professional class. Noticeably heavier (around 20 kg on a 4 × 8 m pool), and handling it without a reel is unpleasant. In return it lasts 3–5 seasons and copes better with UV and chlorine.
The difference between 400 and 500 µm is not in heating — that is practically the same — but in service life. Per season, the more expensive cover usually works out cheaper, provided you have a reel for it.
Colour and transparency: blue, clear or silver?
The colour of the cover changes the balance between heating and suppressing algae growth:
- Clear (transparent) — the highest heat gain, but light reaches the algae as well. Suitable where disinfection is reliably under control.
- Blue — the most common compromise: slightly less gain than clear, better looks and mild shading.
- Silver / grey top layer — reflects radiation back, so heating is the lowest, but the cover is more resistant to UV. It makes sense on pools with a heat pump, where what you want from the cover is mainly reduced evaporation.
The rule for a laminated (two-colour) cover: the darker or reflective side always faces up, bubbles down. We will come back to this, because it is the single most common mistake.
Winter cover: it does not protect heat, it protects the water
A winter cover is an opaque fabric (PVC or heavy-weight PE) with metal eyelets around the perimeter, tensioned with ropes to anchors set in the paving. It does not lie on the water — it sits above it. Its job is simple: to keep leaves, snow, dust and light out of the pool. The darkness beneath the cover stops algae growth, so in spring you open up water that is merely cloudy, not green. The cover also protects the liner from staining caused by rotting leaves — more on that in Leaves, pollen and insects in the pool.
When choosing, watch out for water drainage. Covers without drainage holes or a central siphon sag after rain and a pond weighing hundreds of kilograms forms on them, tearing the cover at the eyelets. The complete end-of-season procedure is described in Winterizing a pool step by step.
Safety cover: the only cover that carries an adult
Here we need to be precise, because the word “safety” is used loosely in advertisements. A genuine safety cover is a fabric tensioned by spring tensioners into anchors sunk into paving or concrete, and it is engineered to carry an adult without them sinking down to the water.
The reference standard is the American ASTM F1346; in Europe you will come across the NF P90-30x series, on which most European manufacturers base their products. Certified covers are tested for a load corresponding to two adults and a child, and for leaving no standing water on the surface.
In practice this means: a bubble cover and a leaf net are not safety devices — bubble film is in fact dangerous for a child or a dog, because a body disappears from sight beneath it. The other layers of protection are examined in Child safety around the pool and hot tub and Pool alarms.
There are three drawbacks: the price, the need to drill anchors into the surrounding paving, and the time it takes to handle. Tensioning all the tensioners takes 10 to 20 minutes, so this is protection for the night, for holidays and for winter, not a daily cover.
Slatted cover: above the water or below it?
A slatted cover is a set of hollow polycarbonate slats joined into a continuous deck that winds onto a shaft. In terms of convenience it is in a different league from a cover sheet — covering and uncovering takes under two minutes and one person can do it at the press of a button. The difference between the variants lies in where the shaft is wound:
- Above-water — the shaft rests at the end of the pool on bearers or in a low chest above the paving. Cheaper, and it can be retrofitted to an existing pool. The drawback: a visible roller and an obstacle on the terrace.
- Below-water — the shaft is hidden in a compartment below the water line behind a dividing wall. It looks clean and nothing gets in the way on the terrace. But it has to be planned during construction, it takes up 60–80 cm of the shell’s length and it is considerably more expensive.
Solar gain and what a slatted cover cannot do
Transparent slats work as insulation and as a passive solar collector — the air inside the cavity warms up and passes the heat to the water. The benefit is lower than with a bubble cover, but a slatted cover holds heat overnight.
What a slatted cover cannot do: it is not automatically a safety device. Systems with end locks and certification to NF P90-308 can be considered a barrier; an ordinary slatted cover without locking cannot. If safety is the main reason for the purchase, ask specifically about certification.
Leaf net: the cheapest solution to one problem
A net is a permeable fabric tensioned with carabiners to anchors along the edge. It does nothing for heat or evaporation — it only catches leaves, needles and coarse debris before they reach the bottom. It will not hold back pollen or fine particles; the mesh is far too large for that.
It makes sense on pools under trees as an add-on: it is stretched over the winter cover in autumn so that leaves do not sit on it and clog the drainage.
How to choose according to your priority
The quickest route to a decision is to identify your single main priority and choose the basis accordingly.
| Your priority | First choice | Sensible addition |
|---|---|---|
| Warmer water and a lower heating bill | Bubble cover, 400–500 µm | A reel, so it actually gets used |
| Small children or a dog in the garden | Anchored safety cover | Surface alarm, fencing |
| Clean water without daily skimming | Slatted cover or winter cover | Leaf net in autumn |
| Convenience and a dislike of handling | Motorised slatted cover | — |
| Looks and an uncluttered terrace | Below-water slatted cover | Plan it during construction |
| Lowest budget | Bubble cover, 400 µm | Winter cover for winterizing |
Reels: when they pay off and when they are essential
A reel is a shaft on wheels or stands onto which the cover is wound. It decides whether you will use the cover, or whether after three weeks it will stay folded up behind the shed.
- Without a reel — realistic up to roughly 3.5 metres wide and 400 µm thick. Two people can manage it, but it takes time and the cover suffers.
- Manual crank reel — the standard for family pools up to 5 × 10 metres. One person can operate it and winding takes a minute. Price €160–480 depending on span and material.
- Motorised reel — on pools over 5 metres wide or with 500 µm covers this is no longer a luxury but a condition of regular use. Prices start at around €1,000.
On pools longer than 10 metres or wider than 6 metres, handling by hand is practically impossible — the weight of the wet film grows with the area. There the choice is between a motorised reel and going straight to a slatted cover.
Correct use: five rules that decide service life
Most covers do not reach the end of their natural life — they are destroyed first. These points make the difference between two seasons and five.
- Bubbles down. The cover is laid with the bubbles towards the water — only then does the air insulate and the surface touch the water. A cover laid the wrong way up heats far worse and the bubbles are destroyed faster. The most common mistake among new owners.
- Take the cover off before shock chlorination. A high chlorine concentration directly beneath the film will reliably destroy it. The cover goes back only once free chlorine is back below 3 mg/l. The same applies to stronger doses of algaecide.
- Let it dry before storage. A wet folded cover in a plastic bag means mould, odour and stains you will never get out. Rinse it, dry it and store it loosely rolled in the shade.
- Do not leave it folded in the sun. In a heap beside the pool the air in the bubbles expands and the film overheats — degradation is an order of magnitude faster than on the water. Either leave it wound up with a UV protective wrap, or move it into the shade.
- Do not drag it over paving. Every shift across block paving means hundreds of scratches and torn bubbles; a slatted cover is damaged by sand blown between the slats. The solution is smooth, clean pool surroundings — see Pool surroundings: paving and decking.
What shortens service life the most
1. High chlorine. A permanent level above 3 mg/l, and above all shock chlorination with the pool covered, degrade the film faster than anything else — it goes brittle and the bubbles start to burst. Long-term low pH has the same effect.
2. UV radiation. Better covers contain a UV stabiliser, and that is the main reason for the price difference between otherwise equally thick products. A cover taken off and left on the terrace degrades faster than one on the water, because the water is not cooling it.
3. Mechanical stress. Dragging across paving, the sharp edges of steps, and wind that lifts the cover and beats it against the coping. On a slatted cover, sand and grit ground in between the slats.
Covers and slatted covers through winter
A bubble cover does not belong on the pool in winter. It does not have the strength to carry snow, and frost and ice will destroy it within a season. It goes away dry and a winter cover or safety cover goes on the pool.
With a slatted cover the main issue is snow. A closed cover under a layer of wet snow sags and the slats can break or be torn out of their joints — and that is a repair running into thousands of euros. There are three rules:
- Either wind the cover up and cover it, or leave it closed and clear the snow off it with a soft broom, never a shovel.
- The water level beneath a closed cover must be lowered according to the manufacturer’s instructions, so that ice does not press on the slats from below.
- Floating winterizing devices belong beneath a closed cover to absorb the pressure of ice — just as in a pool without a slatted cover.
A winter cover should be checked at the eyelets and ropes before it is fitted, because that is exactly where it tears. And the water beneath it must be chemically prepared — the cover alone will not stop the water going green, it will only slow it down considerably.
Frequently asked questions
How many degrees does a solar cover really add?
In central European conditions the real benefit is usually 2–5 °C compared with an uncovered pool, and the larger part of the effect is not in heating but in the water not cooling down overnight. Much depends on sunshine, wind and how much of the day the cover is in place.
Can I cut a bubble cover to the shape of my pool?
Yes. Bubble film is supplied oversized and is cut with scissors to the outline of the water; the edge does not need sealing. Leave a centimetre of clearance to the walls. Winter and safety covers, by contrast, are ordered made to measure.
Is a slatted cover better, or a safety cover?
A slatted cover wins on convenience and on the fact that it gets used daily, which genuinely saves heat. A safety cover wins as a physical barrier at a fraction of the price of a below-water slatted cover. Combining the two is common: the slatted cover for daily use, the safety cover for holidays and winter.
Why do odour and slime form under the cover?
Organic matter accumulates beneath a covered surface, and where disinfection is low a biofilm develops on the underside of the film. It helps to pull the cover off once every two or three weeks, rinse the underside with a hose and air the pool for a few hours. The permanent solution is stable disinfection, not more frequent washing.
Is a cover worth it even on a pool with a heat pump?
It is — more than in any other case. A heat pump heats water from which heat escapes by evaporation, so without a cover you are heating the air above the pool as well. A cover shortens the pump’s running time and is the fastest-paying investment in the whole system.
So which option should you choose
For most family pools the most sensible combination is a 400–500 µm bubble cover with a manual reel for the season and a winter cover from October to April. Where there are small children, a safety cover anchored into the paving replaces the winter cover. A slatted cover is an investment for anyone who uses the pool daily — and with a newly built pool it makes sense to plan for the below-water version from the outset, because it cannot be added later.
You will find covers, slatted covers, reels and nets in the pool equipment category, and heating and filtration technology in the pool technology section. More pool care guides are waiting in the Guide.
