Selecting The Right Material For Your Pool Cover
What is the difference between foam and bubble covers?
A bubble cover, often referred to as a solar blanket, enables free sustainable energy to be transferred to the water via the cover, resulting in a rise in water temperature. Heating and running costs are lowered as a result.
A foam cover works as a insulating lid. The material is manufactured using foaming agents or by radiating the material to create small air bubbles within he material. This helps to retain the heat that is added to the pool via the heating system however no additional energy will be transferred to the water other than that generated by the heat pump.
The difference in performance between the two depends largely on the foam thickness. Looking only at the heat retention properties, a 5mm foam will provide a 60% saving in heating costs, whereas a bubble cover will provide a 50% saving. This is because both a bubble cover and a foam cover prevent evaporation which is the greatest cause of heat loss in the swimming pool and both use air to insulate the swimming pool surface. So both provide a similar heat saving.
Our swimming pool covers are made from LDPE (low density polyethylene). LDPE is used for its material properties, the material has a density of less then one, allowing it to float on the water, has a good chemical resistance to a large number of common chemicals and a good degree of clarity and tensile strength. The expected lifespan of the material is determined by two factors: the amount of UV (ultra violet) additives mixed with the material to prevent the degradation due to solar radiation exposure on the polymers, and the thickness to withstand the oxidising properties of the pool sanitizers.
The material’s design is an important implication on the cover’s lifespan and performance. The main purpose of the bubbles is to create a insulating air gap between the water and the cover, helping to retain heat within the pool, so because of this a large tall bubble is preferable. However there are other considerations when designing the bubble structure – sharp edges produce stress points and thinning on the material. This was the objective when designing GeoBubble™ – to eliminate these weaker areas to achieve a longer lasting bubble.
It is widely agreed throughout the industry that for a good cover that will last two to three years, the thickness should be a minimum of 400micron. For a longer lifespan, thicker grades are required to allow for enough UV protection and material to delay the oxidising effects of the chemicals within the swimming pool. We have found that 500micron offers a good thickness and is still light enough to be conveniently taken on or off the pool. This is why this thickness has been selected for our high performance products.
For the high performance covers, the 500μm has a specialised UV stabilisation package tailored to provide a expected lifespan of over five to six years. These materials are designed to pay back their investment within the first year of use and are developed to provide the optimum savings available for its specific application.
Why choose a bubble cover?
A bubble cover is lighter and easier to remove from the pool.
A bubble cover is generally cheaper than a foam cover. With high performance Guard covers, the return on investment or payback period is one year.
Foam covers also insulate the pool from potential heat gains from solar energy.
What effect does colour have?
A swimming pool is a high value investment in a sport or lifestyle. The aesthetic value is an important consideration too. Throughout the market there are rich colours that can provide an attractive look to the pool. If making the choice from an aesthetic view point, it is important to consider the sections above as the cover’s ability to reduce, the costs of maintaining the pool will be dependent on its characteristics. Most of the aesthetic colours tend to work as a intermediary between products like Sol+Guard™ and EnergyGuard™ providing some heat gain and some chemical savings but will not have the same lifespan or provide the high performance.
Opaque materials like EnergyGuard™ are ideal for reducing chemical consumption and preventing algae growth. This is because they block the light, preventing photosynthesis and photolysis which deactivates the active sanitizers in the pool. A small temperature increase is produced by the cover absorbing the sun’s energy and heats the pool through radiation and conduction. This makes opaque covers a good choice for pools which are shut down regularly, allowing for chemical free hibernation and faster start up times. In very hot countries where pools require cooling or shading, an opaque material with a high reflective index like CoolGuard™ will help to keep the sun’s energy out of the pool.
Transparent materials are best suited for adding heat to the pool and our tests have shown Sol+Guard™ to be the most efficient. The material works like a glass roof, providing a temperature increase throughout the water by harnessing all of the spectrum within the sun’s atmospheric window. This temperature increase reduces the work required by the heating system to raise pool temperatures, reducing costs and, in warmer climates, can maintain a pool at a comfortable temperature without the need for a heating system.
Why choose a laminated weave?
Again dependent on colour, the woven materials will work as a intermediary between a chemical saving cover (EnergyGuard™) and a solar heating cover (Sol+Guard™) .
The main benefit of laminating the woven film to the material is that the HDPE (high density polyethylene) strands have a higher molecular weight which simply means that the material is stronger. This makes the woven materials more durable to wear and tear.