Plant air in sweep mode is not recommended for these reasons: (a) often plant air can heat-up and if it goes over 25 deg. C, it begins to oxidize the Liqui-Cel membrane (b) a slight vacuum from the blower gives a performance boost over plant air, and (c) If there is a restriction in air flow through the contactor (for example someone shuts-off the outlet valve), the Liqui-Cel will no longer work and will actually turn into a bubbler, and d) compressed air has entrained water and oil.  SnowPure recommends using the suction side of a regen blower instead of compressed plant air. We can help size and source the blower.