My guess on the pool situation is that they shock the hell out of it at 7pm and it probably takes several hours for the water to return to "safe" levels for use, and I assume that all the pools flow thru a central cleaning system. Also, the staff clean the in the water chairs every night so time is needed for that. Just a thought.
We used it almost every day last week. For us it was perfect since we wanted some chill time this trip but yeah, it's usually fairly empty.
I don't know a lot about pools, but I doubt the rooftop pool and beach level pools use a common filtering system. It'd be a lot pumping and weird pressures to deal with. The rooftop pool would act like a water tower. I didn't notice anything specific for sexy pool, but there is a hidden underground area near entrance of Romanza....pretty sure that is filtering for the quiet pool.
I have said it before and I know this will never actually happen, but wouldn't that place make the ultimate play area?!?!?!