Try double-clamping with a tight-fitting O-ring in between the two clamps. If possible, fit the O-ring between the copper and the hose.
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Planned: sLambic II, Flanders Red II
Primary: Fat Man Porter, Orange Blossom Mead, sLambic I
Secondary: Flanders Red I
Kegged: 3 different ciders, Janet's Brown, Barrel-aged Stout, Hallertau Blanc Pale Ale
Bottled: Flanders Red I