Z00L00K writes: [Ars Technica reports:] "After a week of trying to part with green tides in two outdoor swimming pools, Olympic officials over the weekend wrung out a fresh mea culpa and yet another explanation -- neither of which were comforting. According to officials, a local pool-maintenance worker mistakenly added 160 liters of hydrogen peroxide to the waters on August 5, which partially neutralized the chlorine used for disinfection. With chlorine disarmed, the officials said that 'organic compounds' -- i.e. algae and other microbes -- were able to grow and turn the water a murky green in the subsequent days. The revelation appears to contradict officials' previous assurances that despite the emerald hue, which first appeared Tuesday, the waters were safe." I would personally have avoided using the green pools, but that's just me. "Hydrogen peroxide is sometimes used in pools -- often to de-chlorinate them," reports Ars. "Basically, the chemical, a common household disinfectant, is a weak acid that reacts with chlorine and chlorine-containing compounds to release oxygen and form other chlorine-containing compounds. Those may not be good at disinfecting pools, but they still may be picked up by monitoring systems. Hydrogen peroxide can also be used to disinfect pools but must be maintained in the waters -- not a one-time dumping -- and can't be used in combination with chlorine." Apparently, the green water irritates eyes and smells like farts.