Swimming Pool Covers
Swimming Pool Covers, as the name suggests are simply a means to place a barrier between the surface of your swimming pool and the outside environment, but don’t be fooled into thinking that means you only need them with an outdoor pool
There are 3 main reasons why you should have a pool cover:
Swimming pools lose heat mostly by evaporation and convection. This is because water is a highly effective carrier of heat, which is principally why it is widely used as a coolant. To understand the impact of evaporation on your swimming pool temperature, consider that it requires around 2.4MJ of energy to evaporate 1 kg of water at 25C. Over an average year for a pool that is 8m x 4m, 160 litres (which is 160kg) of water will evaporate in a day, averaging to over 20,000 litres in a year. That takes about 48,500MJ of energy out of your pool over a year – which equates to 13.5MWh of electricity, or over £2,000!
Pool covers reduce the evaporation from indoor pools as well as outdoor ones and it is estimated that up to 50% to 70% of the pool heating costs can be reduced with an effective cover. So you could save between £1,000 and £1,500 per year just on the heating costs.
This is an obvious one – when the pool is not in use it is important to ensure that there is no risk to children, pets or wildlife to falling into the pool. Obviously this will be a greater consideration for some pool owners than others – if you have an indoor pool with no children and no pets then the risk is far lower than for an outdoor pool at a home with animals and young children.
Obviously in ground swimming pools are the greatest risk, but above ground pools also present a hazard, and consideration should be given to this when selecting a pool cover. The only truly safe cover type is a Safety Cover and if this is a concern for you then you should not consider other cover types.
Having a physical barrier over your pool will reduce the opportunities for debris such as leaves and dirt to enter the pool. Debris that does get into the pool will start to break down and will cause both particle pollution in the water and may upset the chemical balance, leading to cloudiness or other problems which can be expensive to treat and put the pool out of use temporarily. In this case prevention is definitely better than cure and a pool cover can ensure you get the maximum use from your pool, with less frequent pool cleaning.
A slatted pool cover on a roller
An in ground pool solar cover
Types of Swimming Pool Cover
The main types of swimming pool cover are:
- Winter Debris Cover
- Solar Cover (also known as a bubble cover)
- Slatted / Venetian Covers
- Safety Covers
- Rolling Deck Covers
- Moving Floor Covers
Winter Debris Covers
Winter debris covers are the simplest type of swimming pool cover and consist of a mesh that will allow rainwater through but prevent leaves and similar debris from entering the pool. They are typically installed as part of the decommissioning process and removed when the pool is recommissioned.
Solar Covers are the simplest year-round cover, and consist of a pair of layers of flexible plastic sheeting with air bubbles between the two. It is generally the cheapest option but is often manually operated (ie you have to remove it and replace it by hand) and has the shortest lifespan.
On a sunny day, a swimming pool solar cover will allow sunlight to pass through it, which will warm the pool water. This will have a beneficial effect on heating costs.
They are not safety covers and cannot be counted on to keep children or pets safe when the pool is unattended.
Slatted / Venetian Covers
Slatted Pool Covers typically have rigid slat construction. Similarly to the solar swimming pool cover they float on top of the pool. The slats themselves may be made of uPVC or polycarbonate and are interlocked so that they are flexible in one direction (usually across the length of the pool) whilst being rigid in the other. As a result of this rigidity, they are deployed and retracted via a roller at one end, either manually or automatically. Polycarbonate covers typically have more durability and longer lifespan than uPVC but as the raw materials are up to 25% more expensive, they are a more expensive option. Slatted covers can accommodate shaped ends of the pool.
Whilst some solar heating of the water will occur, they are not a sealed barrier and so losses through evaporation will at least partly offset this.
However, whilst they are more robust than solar covers they are not safety covers and cannot be counted on to keep children or pets safe when the pool is unattended.
Swimming pool Safety Covers are designed to be able to withstand an adult or child falling onto the cover and are obviously a good choice for families and pet-owners. They are typically made of heavy duty, vinyl material and may be supported with bars or runners along the side of the pool and can be manual or automatic, and can be deployed via a roller.
Unlike solar or slatted covers they provide a complete barrier between the pool water and the environment so in addition to their safety properties they also provide a superior reduction in evaporation. However, this also means that they fully block out sunlight, which means that there is far less warming of the water from the sun whilst the pool is not in use.
The nature of a Safety Cover means that it completely isolates the pool from the elements in a way that solar covers or slatted covers cannot so if leaves from trees falling into the pool are a consideration then you should opt for a Safety Cover.
Rolling Deck Cover
A rolling deck cover is suitable for pools or hot tubs that are inset to a decked area. It is a hard swimming pool cover and consists of an area of deck mounted on runners, such that it can be rolled back to reveal the pool. These may be manually or automatically operated, although are obviously heavier than the other pool cover options above, and require a large area to roll onto, which may make them impractical for many pools. That said, they offer excellent safety and insulation due to their solid construction and as an added benefit, they can typically be used as a normal deck when the pool is not in use.
This is only suitable for a new pool build, and would always require a detailed feasibility assessment.
The Moving Floor cover is the most advanced and expensive solution. In this approach the floor of the pool is designed to function as the pool cover. When not in use, the floor is raised, the water drains below it and it sits flush with the surrounding area. This is clearly a great option for providing multi-purpose space and being able to use the area for other things when the pool is not in use, but unsurprisingly it is also a substantial piece of engineering and carries a price tag to match.
This is only ever suitable for a new pool build, and would always require a detailed feasibility assessment of the whole site.
Pool Cover Life
The swimming pool cover itself is exposed to a variety of factors which will cause degradation and damage over it’s lifetime, principally UV sunlight for an outdoor pool (and if you’ve ever left plastic items out in the sun for an extended period you will be familiar with the way in which UV light makes plastics age, fade and become more brittle and prone to tearing) and the pool chemicals in the water. You can minimise the impact of the pool chemicals by ensuring that your pool is well maintained and balanced, but should keep your pool cover removed when chlorine shocking the pool (until chlorine levels return to normal) to avoid corrosion of the cover. Of course a compounding factor is the heat accelerates these processes so a warmer pool will increase the rate of deterioration.
Typically, a solar pool cover may only last 3-5 years, whilst the vinyl in a pool safety cover may last 5-10 years and a rolling deck will last a lot longer provided it is properly maintained. As with many things a cheap pool cover may be a false economy if it deteriorates faster than a more expensive one so it is best to get advice on what is right for the situation of your swimming pool.
Also bear in mind that any cover will prevent chlorine from evaporating from your pool as a gas, which means the concentration in the water will remain higher whilst the cover is closed – meaning you will need to ensure your chlorinator is properly set to allow for this (typically 30%-60% lower depending on the cover type and ambient conditions). As with all things related to swimming pools – if in doubt, consult an expert to ensure this is set correctly.