So........recently shelled out a lot of "doe" for a brand NEW fluval 406 and 306 because of the "quiet" ratings it receives on almost all reviews (except for forums).Bottom line up front, they are both LOUD! The impellers make a grinding noise. What is most disappointing is that my 406 was silent at first and is now grinding.
I have tried everything:
the teflon tape on the impeller housing
teflon tape under the impeller itself to better lock it into place
purchased all new motor head kits and replaced already BRAND NEW parts
tried silicone lube on all the parts
I have had many canisters and can't seem to figure these out. The filters are properly primed and all parts are in order. The only air in the system is when I break them down to try and fix the grinding noise and restart them. Customer service is non existent.