The news said the kids got into trouble then the dad jumped in after them and got into trouble as well. I can understand cold or a medical condition affecting one or at a stretch but all three including a grown man? News also said they got pulled into the centre then presumably went under. I'm going with filtration system myself. Obviously no-ones going to own up to switching it on/forgetting to switch off in the morning they'd be facing manslaughter charges and the hotel well they don't want anything affecting their reputation so they'll hush it up/want to blame the family/freak accident.
Amazing how everyone turns into an armchair expert eh?
The filtration system runs 24/7. Your theory is utterly incorrect.