One of the frothiest stories to bubble forth from the shit-tastic Rio Olympics this week was the sudden, inexplicable greening of not one, but two Olympic pools. Actually, there is an explanation: algae. Lots of them. Alternately, the viridescent hue might have been caused by a simple chemical imbalance.
Methylene blue - Wikipedia
Cloudy swimming pool water is caused by low Free Chlorine, debris, ammonia, poor filtration system, and wrong chemical levels. The recommend level of FC is 3ppm and should never go below 3ppm otherwise your water will turn cloudy, which means you have chloramine or combined chlorine in your water. If you have a saltwater swimming pool and it's cloudy; firstly, measure your FC level. If FC level is below 3 ppm and the percentage settings in your Saltwater Chlorine Generator SWCG is high or your pump's speed is already high and you can't raise FC level in your pool, you need to shut down your SWCG and shock your swimming by adding chlorine manually like a non-saltwater pool. Foreign particles, debris, or dirt may cause your pool water to turn cloudy or look dull. Always before assuming any cause of cloudy pool water, take accurate reading of FC and make sure it's 3ppm. To clear cloudy pool water caused by debris faster, use Pool Clarifier to remove all the particles in your water through the filter and then backwash your filter to clean it.
In this comedy movie I saw, there was a chemical in the pool that turned urine dark blue. I'm probably going to have to go to this specific water park this weekend not naming names here and most people who go to it have no class and would gladly urinate in the pool as a "more convenient" alternative to using the restroom. There are chemicals called pH indicators the pH scale measures the strength of bases and acids and the indicators change color depending on their environment. BTB in a neutral or base pH environment is the color of blue you saw in the movie.
Ok, the concept of swimming around in a urine infused pool is disgusting! However, when it comes to the choice between sizzling in the sun and taking a nice fresh dip, there are few of us who can resist — pee or not! As it turns out, one in five members of the public openly admit to having peed in the pool in their lifetime!