Tuesday, July 15, 2008

Trend watch: Saltwater pools

They're the hottest technology in cooling off to come along in years. And they could make the stinging eyes, itchy skin and bleached bathing suits of old-fashioned chlorine pools a thing of the past.

First introduced in Australia in the 1960s, saltwater pools have taken off in the last few years to become the fastest-growing technology in new pool installation, even though the initial cost is considerably higher than a standard chlorine system. But converts say that once you've tried it, you can never go back.
Just ask Priya Mohan, a secondary school teacher and mother of three who lives in Burlington, Ontario. "When we did our backyard renovation a few years ago, we definitely knew we wanted a saltwater pool," she says. "It's better, in almost every way, than a chlorine pool. It's easier on your eyes, the water is much softer and less irritating, and maintenance is much easier too -- you add a bit of chlorine at the beginning of the season, and that's just about it.

The merits of saltwater pools

Though the water in a saltwater pool is saline, it's actually nothing like swimming in the ocean. The salt concentration in the pool tops out at about 2800 to 4000 parts per million, compared to 50,000 parts per million in ocean water. Saltwater pools are less salty than tears (you usually can't even taste the salt) but the soft, luxurious feel of the water, not to mention freedom from the burning feeling of too much chlorine, is immediately noticeable.

Understanding how the technology works requires a quick review of Grade 10 chemistry. Standard chlorinated pools rely on an erosion feeder system, whereby chlorine pucks are inserted into a canister to melt or "erode", adding chlorine to the water.

Apart from the costs involved with regularly replenishing the chlorine pucks, the danger of spikes or dilution after a rainstorm requires that you test and adjust the chlorine levels regularly, as well as "shocking" the pool from time to time with larger infusions of chlorine.

Saltwater pools also use chlorine as a disinfectant, but in a lower concentration, and it's supplied to the water in an entirely different way. Instead of an erosion system, a built-in generator uses a form of electrolysis to separate water molecules into hydrogen and oxygen, and then combine them with salt (sodium chloride) to form sodium hypochlorite (chlorine), which sterilizes the water.

At the same time, the chlorine thus created is also constantly recombining with the sodium, becoming good old salt again. It's a closed, continuously regenerating process that once started -- with an initial application of chlorine and salt at the beginning of the season -- needs adjustment no more than once or twice a season at most.

Less costly long-term
According to Markus Brunner of Forest City Pool and Patio in London, Ontario, initially installing a saltwater system can cost as much as two to four times as much as a standard chlorine erosion system. But once you factor in the savings in chlorine pucks and other chemicals, as well as reduced maintenance and wear and tear on the pool itself, he estimates that a saltwater pool can pay for itself in as little as three years.

Existing chlorine pools can be converted to saltwater relatively easily as well, by simply adapting the existing plumbing to accommodate the generator. Brunner claims the only possible risk is to metal ladders, that if not properly grounded, can oxidize over time when exposed to the electrolyzing process. As for the Mohans, they couldn't imagine any other way to beat the heat. "We're spoiled," says Priya. "None of us will even go in a regular chlorine pool any more."
Source: MSN

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