Inkjet printer with float valve regulation of hydrostatic ink pressure

An inkjet printer includes: an inkjet printhead; an ink reservoir containing a supply of ink; and a pressure-regulating chamber for maintaining ink contained therein at a predetermined first level. The chamber includes: an inlet port connected to the ink reservoir via an ink supply line; an outlet port connected to an ink inlet of the printhead via an upstream ink line; an air vent open to atmosphere; and a float valve for maintaining the predetermined first level of ink. The float valve includes: an arm pivotally mounted about a pivot; a float mounted at one end of the arm; and a valve stem attached to the arm, said valve stem having a valve head for closure of a valve seat, the valve seat being positioned at the inlet port of the pressure-regulating chamber.