An inkjet printer includes: an ink reservoir; a printhead having an ink inlet and an ink outlet; an upstream ink conduit connected to the ink inlet; a downstream ink conduit connected to the ink outlet; and a pressure-regulating chamber. The pressure-regulating chamber includes: an inlet port connected to the ink reservoir via a supply conduit; an outlet port connected to the upstream ink conduit; a vent open to atmosphere; and a float valve for maintaining a set level of ink in the pressure-regulating chamber. The float valve includes: an arm pivotally mounted about a pivot; a float mounted at one end of said arm; and a valve head connected to the arm for sealing engagement with a valve seat at the inlet port.