Need help with RO solenoid shut-off

[TANGOMAN]

There is a "fluttering" noise, very faint though. My set-up is not continuously open though. I run lines up to reservoirs behind the tanks contolled by a float valve. That reservoir then gravity feeds to the sump through another float valve. None of the reservoirs are "pressure fed" unless I open the inlet valve to the RO unit. I still want to do that "garden hose timer thing" as sometimes I leave the inlet valve open and that has potential for bad things to happen...not that they ever happen to me.
I hear the noise only when I'm beside the unit and it has been "shut-off" for a few minutes. Balancing pressure through slow leakage was my assumption...?
But we too have cats so maybe it was him ? There is usually another sense that is stimulated shortly after hearing that sound...much like your cat demonstrated to me
With the relentless heat of the past few weeks and the fans goin' full tilt to keep 'em cool, I'm evaporating like crazy too !
Tubing ? Aaaah...flexible copper (Cu) of course ! Whaddaya think I'm stupid. (Don't answer that...). I'm not certain what it's called , I'll assume it is. I thought pex was grey and not available any smaller than 1/2" dia. Mine is "cloudy white" 1/4" flexible. I am of course still refering to the tubing... MAO...