same thing happened to me when i first bought it and after i was done setting it up started making noises,took apart find a small rock in the pump....now works great...i love it....!
After cleaning my Fx5, i just fill the canister to the RIM with declorinated water,put the lid back on,make sure all the locking nuts are tight,open the valves plug it in! Ive been doing this since i first got one years ago! and ive never had any problems or weird noises comming from any of them!
