Maybe you're wrenching it on too tight to begin with. The compression rings will do a pretty good job of keeping the water in the canisters even without cranking down on them full force.
if it starts to leak, release the pressure and just tighten it a half inch or so and you're good to go!
When you crank it down, then add water pressure, you're binding the fittings, then need extreme torque to get them 'unbound' (if you will.) My only concern about this advice is that you've compressed the compression fittings to hard now, they may leak unless you continue to torque them down.
I've had mine for about a year and LOVE IT!!! Then again, New Jersey has very bad water and this thing is a life-saver ... or should I say "spot"-saver?