Review on Marineland Polishing Internal Canister ML90770 by Joshua Weaver

Too bad 4.5 stars are not available. My filter, like many others, was making a frequent and annoying 'hum' which really annoyed me and must have been awful for the fish. It was also often clogged and stopped working. I was confused. I cleaned it every couple of weeks and just put up with the noise (which wasn't always, but was frequent and sporadic). Then one day the filter stopped working again and I cleaned it and put it back together. Also clean, it didn't work. I disassembled it and looked at all the components. I assumed it was the engine so I called Marineland and the support was excellent. The American representative approached me and after some discussion sent a replacement. When the new one arrived I accidentally spun the impeller and it offered VERY strong resistance. I pulled the motor out of my unit and the impeller spun freely. Then I put the new magnet/impeller in the old motor and it had a lot of resistance. So I looked at two impellers: Both nodes have a plastic "weld" or recess that matches the cam on the impeller shaft. The new impeller was also glued to the magnet and could only rotate half a turn to the stop. The old block was not (already) glued and seemed to detach from the cam, allowing it to spin freely - and therefore not getting any grip as the motor turned the magnet. I replaced the impeller and got instant and quiet operation. My guess is that early batches of this product didn't have a reliable enough impeller and so there was noise as it 'bounced' and corroded the plastic cam stop until it finally failed. The company took great care of me and I am very happy with this decision. EDIT: After two weeks the buzz is back. I'm still positive that the problem with the impeller and impeller housing is just the moving part. Another reviewer said it cleans up every time it starts buzzing. i can try that EDIT 2: I can confirm that cleaning the filter stopped the buzzing - and it was dirty after two weeks. I feed sinking pellets next to the filter. I think I'll switch to the other side of the tank.