Methods and apparatus are presented for controlling fluid flow through flow paths with pressure gradient fluid control. Passive fluid flow barriers may be used to act as valves, thereby allowing the flow of fluids through flow paths to be regulated so as to allow fluids to be introduced via a single channel and subsequently split into multiple channels. Flow through the flow paths can be regulated to allow a series of sister wells or chambers to all fill prior to the fluid flowing beyond any one of the sister wells or chambers. Each flow path may have multiple segments, at least one of which is designed to balance the pressure drops of the flow paths to provide uniform flow of fluids through the flow paths. The configurations of the wells may also be modified by adding vents or flow dividers to enhance fluid flushing and gas removal capability.