If I prime it a few times the noise will go away I checked all the grey rubber pieces everything is tight the only thing I can think thats leaking air is the thing on top that controls water flow where the tubes go out and in
I bought a fluval 207 the impeller is making a crackling noise after a while so I bought a rebuild kit and yet after a few hours it eventually makes a loud non stop crackling noise and sometimes it's worse at full throttle what could this possibly be it's annoying