There are many factors that you need to consider when planning a new fish room, but one of the first is to decide what size tanks are needed and a lay out for the racks (at least a rough layout… the final result rarely fits exactly). The numbers and sizes of the tanks will define the racks, which in turn will guide the layout. The other systems are dependent upon that. Think of the aquariums and racks as the functional skeleton of the fish room. It is the framework around which the rest of the room will be built. Here is a video about the tank sizes I used, the racks I built for them and how they are laid out in the room to make use of space.