Flussbad Gartenstraße is a youth club in Berlin that provides young people with a place for leisure and community. Unfortunately, the available material for the website primarily contains information about a software developer and their technical services, not about the youth club itself. Therefore, no reliable, concrete information can be extracted from the provided content regarding the actual offerings, activities, age groups, or opening hours of the club. To provide you with a warm and factually correct description, I would need current information directly from the youth club — such as the premises, regular programs, events, and how your family can participate.