Sort:  

I was in the weekend when it's crowded. There are many swimming pools and I did not mind that there was a lot of people, not everyone spends a whole day at the spa, some of them buy a ticket for only 3 or 5 hours. During the week it's better.

Ah, I see, they have hourly tickets, interesting! Thanks for the tips and feedback. I've yet to make it to Bucharest but I'm surely going to add this to my "must do" list.