A media cartridge configured to be operatively associated with a head assembly comprising a drive and an adjuster, the media cartridge comprising a sump and a sump cover, the sump cover having an inlet and an outlet, the media cartridge further comprising: a feed chamber and a mixing compartment, the inlet in fluid communication with the feed chamber and the outlet in fluid communication with the mixing compartment; a media compartment containing an ion exchange media; a bypass port in fluid communication with the feed chamber and the mixing compartment; and a bypass regulator that is adjustable by linear movement, the bypass regulator comprising a normally closed, adjustable bypass regulator that uses a spring for closure; wherein a first fluid path is present between the feed chamber and the media compartment such that fluid flowing through the first fluid path contacts the media to form a treated fluid that enters the mixing compartment; and a second fluid path is present between the feed chamber and the bypass port such that fluid flowing through the second fluid path does not contact the media and is untreated upon entry into the mixing compartment, the media cartridge further comprising a filter element in the mixing compartment and a filter element cover and an end cap sleeve containing the filter element, the filter element comprising an upper end cap, a lower end cap and a filter core, the upper end cap having an extension with a section of enlarged diameter, which when lined up with the bypass port blocks flow into the mixing compartment and when not lined up with the bypass port permits flow into the mixing compartment, an amount of bypass fluid flow being varied depending on location of the bypass port relative to the section of enlarged diameter, wherein when the media cartridge is operatively associated with the head assembly, the drive imparts linear force on the bypass regulator in order to adjust the amount of the bypass fluid flow. a feed chamber and a mixing compartment, the inlet in fluid communication with the feed chamber and the outlet in fluid communication with the mixing compartment; a media compartment containing an ion exchange media; a bypass port in fluid communication with the feed chamber and the mixing compartment; and a bypass regulator that is adjustable by linear movement, the bypass regulator comprising a normally closed, adjustable bypass regulator that uses a spring for closure; wherein a first fluid path is present between the feed chamber and the media compartment such that fluid flowing through the first fluid path contacts the media to form a treated fluid that enters the mixing compartment; and a second fluid path is present between the feed chamber and the bypass port such that fluid flowing through the second fluid path does not contact the media and is untreated upon entry into the mixing compartment, the media cartridge further comprising a filter element in the mixing compartment and a filter element cover and an end cap sleeve containing the filter element, the filter element comprising an upper end cap, a lower end cap and a filter core, the upper end cap having an extension with a section of enlarged diameter, which when lined up with the bypass port blocks flow into the mixing compartment and when not lined up with the bypass port permits flow into the mixing compartment, an amount of bypass fluid flow being varied depending on location of the bypass port relative to the section of enlarged diameter, wherein when the media cartridge is operatively associated with the head assembly, the drive imparts linear force on the bypass regulator in order to adjust the amount of the bypass fluid flow.