Though hotel staff claims the pool contains salt water, instead it seems merely non-chlorinated and almost magically pristine.

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Sandy motel floors, over-chlorinated pools, and too much junk food?

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It was not the best of facilities - my locker door was busted, the shallow pool was excessively chlorinated and there was nothing hot about the hot tub - but floating in a rooftop pool before getting on my flight capped off what was the most fun I have ever had in an airport and led to a deep, relaxed sleep on the plane.

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Thomas Lachocki, the CEO of the National Swimming Pool Foundation, says that in order to be properly chlorinated, pools should contain 1-4 parts per million of chlorine and pH levels should be within 7.2--7.8.

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Many pools are moving away from boxy or circular shapes and chlorinated water and are instead installed in eye-catching geometric shapes with saltwater.

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Last year the state of California added the commonly used flame retardant TDCPP (chlorinated Tris) to its list of known cancer-causing chemicals.

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