World's largest salt-water swimming pool: but how to keep it clean?

The Electric New Paper 19 Nov 07
LAP OF LUXURY

IF you ever stay at the San Alfonso del Mar resort in Algarrobo in South Central Chile, you need to be very specific when you tell your friends to meet you 'by the pool'.

Otherwise, you could end up waiting for each other on deck chairs 1km apart.

This is because the pool at this luxury resort is so big, you could do laps in it using a sail boat.

Acknowledged by Guinness World Records as the world's largest swimming pool, San Alfonso del Mar's pool makes the previous record holder look like a wash basin.

Completed in December last year, this salt-water lagoon stretches over 1km in length and covers 8ha, an area equivalent to about 66 Olympic-sized pools.

In comparison, the next largest pool in the world, the Orthlieb pool in Casablanca, Morocco, measures only 150m by 100m.

Size isn't only this pool's claim to fame.

Ringed by a private white-sand beach, the pool features its own boat slips and docks from which visitors may rent kayaks and sail boats for cruising on its calm waters.

It also has a ferry to take you from one end of the pool to the other if you end up waiting for friends at the wrong side.

The water, which comes from the Pacific Ocean, has the intense turquoise colour of tropical seas and is crystal clear to a depth of 35m.

Water temperature is also at a comfortable 26 deg C in summer, or about 9 deg C warmer than the ocean located just yards away.

And the purification technology for the pool is so advanced that its creator claims that the water is clean enough to bathe in.

$2 BILLION

As you can imagine, it's not cheap to build a pool this size.

It cost about US$1.5 billion ($2.2b) to build, and takes roughly US$4 million a year to maintain.

This Chilean oasis, about 110km west of the capital Santiago, did not sprout up overnight.

It took its creator, Chilean biochemist and real estate developer Fernando Fischmann, about a decade to devise a way to maintain the cleanliness and clarity of such a large body of water.

He came up with the idea for a gigantic pool to go with the resort in 1997 because he felt it needed a radical attraction that would set it apart from competing resorts.

At the time, visitors' options for water activities there were limited because the waters off the coast of Chile were too cold and inhospitable.

That's when Mr Fischmann decided to create a giant pool for them.

The only problem was that back then, technology that could purify such a large body of water at low cost did not exist.

So he developed the technology himself.

It was only last year that his crystalline lagoon technology was finally ready for the market, and he debuted it at San Alfonso del Mar.

According to Mr Fischmann, his way of keeping the pool water clean and clear uses a 'pulse-based disinfection' method that requires up to 100 times less chemical products than traditional methods.

Unlike regular swimming pools that filter water continuously, Mr Fischmann's technology reportedly makes use of 150 in-wall sensors to surgically clean only the dirty parts of the pool's 2.5 million litres of water.

The pool's sheer size also helps dilute the concentration of any contaminants.

Following the success of the San Alfonso pool, Mr Fischmann set up a company called Crystal Lagoons to market his pool technology to other resorts, especially those in places with no access to beautiful waterfronts.

'It is a technological process and a one of a kind architectural concept adaptable to forests, marshes, deserts, urban areas or areas without beaches,' he told TradeArabia News Service.

'They can also be created on overcrowded or eroded coastlines, contaminated seas or rivers and dangerous or inhospitable beaches.'

The company is already in the midst of creating other megapools in Argentina, Panama, and Dubai.

PURITY WON'T LAST FOREVER?

However, some experts have expressed doubts that Crystal Lagoons' purification technology can keep these pools sparkling clean indefinitely.

Mr Ralph Keller, an expert in industrial hygiene, told Wired magazine that the principles behind the method are sound, but may work only for the short term.

He said: 'For the first few years, it may just be the size of the pool that's keeping it clean.'