Infinity pools are also known as vanishing edge or negative edge pools. They have one or more sides where the pool edge terminates in a weir that is 15 to 25 mm lower than the median pool water level. The water cascades over the weir into a collection trough that runs along beneath the whole length of the weir. The effect when viewed by a bather in the pool is very dramatic when the edge appears to merge with sea in the background or even the sky if the pool is located high up on a hillside.
A properly designed infinity edge pool has two circulation systems. The infinity edge system is only designed to run when the pool is being used and consists of a circulation system that takes water from the collection trough, filters it and returns it to the main pool. The other system works in exactly the same way as a conventional pool, filtration and heating circulation system except that the ugly conventional skimmers are not required and the water circulates back through the pump via the drain in the pool floor.
The additional cost of an infinity edge pool arises mainly from the provision of:-
- The collection trough that acts as a buffer tank
- The water-proofing of the weir and the collection trough
- The large capacity infinity edge circulation pump and filter
- The electronic autofill sensor in the collection trough
The automatic level sensor / filling device is needed to ensure there is enough water in the system to prime the edge pump and to compensate for any waves sent over the weir by bathers and rainwater. For a 12 x 6 metre pool with one infinity edge the additional cost should be in the 8 to 10,000 Euros range excluding any taxes. The trough and autofill, edge filtration system and the additional water proofing costs will each amount to about one third of this or about 3,000 Euros each. The water-proofing may seem to be costly but a conventional factory made PVC liner is not suitable for an infinity edge pool and needs to be replaced by a PVC “liner armee” system that involves cutting and welding the PVC liner on site.
There is a very interesting alternative to infinity edge pools that is beginning to be sold into the French pool market where Bluepools operates. These are called mirror pools and they are an exciting option when the views from a garden are less than spectacular. In a mirror pool the infinity edge is taken around the entire perimeter of the swimming pool and the weir is drained by a perimeter trough that is much smaller than the collection trough of an infinity pool. The perimeter trough is drained by a network of gravity fed downpipes that take the water to a central collection tank that provides the buffer water storage normally provided by the collection trough in a conventional infinity pool. The cost of a mirror pool will be a little more than the cost of an infinity pool of the same size with the infinity edge along one long side.
The additional operating costs of either an infinity or mirror pool will not be that high because the big pump needed to run the infinity edge system will only operate when the pool is in use. The extra costs will be incurred from:-
- The power the pump uses
- The cost of the water that is lost due to evaporation from the flow over the weir
- The cost of replacing the heat loss caused by evaporation
- The heat required for the water replacing the evaporated water
The total additional operating cost is difficult to assess accurately because it does depend on so many variables but it will certainly be less than the cost of heating a conventional pool of the same size using a heat pump.
The development of infinity pools has coincided with the increase in a new trend towards designer pools that are now often seen at exclusive properties and on magazine covers. Many people have property in an ideal location for the installation of an infinity edge pool even more have gardens that would benefit from a mirror pool and I hope this article encourages the development of both.
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