Main problem: The HW-302 canister filter has a terrible rattling noise. I have checked the rotor and the impeller and everything is it's place. I have also tried another rotor & impeller but the rattling noise is the same. There is no air inside and all parts including filter media are mount in the right way. So the only reason the rattling noise seems to be the poor design of SunSun HW-302 Canister Filter. Secondary problem: The water flow is advertised as 1000 liters / hour, but in reality the flow is 650 liters / hour.