[TheeMon]

ok i have 2 ac50s(aka 300s) anyways 1 is super loud and 1 is not.. yesterday i went and tore both apart to see if anything was different, there not, both impelers are the same too, there both perfect. my question is why is 1 loud when the others not...

also if it makes a difference the loud one has a hard time starting after the power has been shut off.

 

[MalawiLover]

You may have a grain of sand or something in the impeller shaft area. Also, check the shaft for any damage to the little plastic end caps. I had one with a small crack in the shaft cap and it sounded like I poured a handfull of sand into it.

If you can't see and damage, try swapping the impellers. If the sound transfers then you just need to replace the damaged impeller.

 

[bones06]

When mine was making noise I found that the lid over the top was causing it. It eventually stopped after I played with the fit.

 

[Rick_Lindsey]

When mine was making noise I found that the lid over the top was causing it. It eventually stopped after I played with the fit.

At one point I set something on the lid to make it quit rattling. Eventually I just took it off (though that has drawbacks... more water evaporates which can also lead to mineral deposits)

-Rick (the armchair aquarist)

 

[TheeMon]

actually i took the lid off allready, it heppened but not enough...

no sand, no substrate, the impeller part looks perfect, i pulled the quite one out to compair them... id prefer not to do that again... it took me a hour to start the noisey one again...

 

[BrianNFlint]

Put vaseline on the magnetic part of the shaft to give it a little lubrication. This should solve your problem.

 

[BrianNFlint]

oops. double post. if possible please delete.