Fluval 403

[TurtleMan]

Hello fellow members,

I've had 2 Fluval 403 filters since new, & they have been extremely reliable.
Recently, after cleaning / carbon replacement, I can't get the flow started again on either of them, despite my usual procedure & vigorous shaking.
The impellers start up right away, and the hoses seem clear
I like them so much that I have a good stock of new OEM parts - so that's not the problem.

[Biulu]

Have you filled the canister with water to the rim before starting it back up?

[new_hobby]

You may have to fill up the hoses as well.