rtk wrote:
Unplug and TAKE THE CANNISTERS OUT OF THE WATER. Take it all apart at
the sink, rinse it and put it back. Make sure the inside of the
cannister feels smooth or it will be difficult to get apart next time.
Been there, done that.

In answer to myself: I will write on the blackboard 100 times that a
Fluval 404 is not a Fluval 4+. Everything I advised with such great
authority should be tossed out.

Ruth Kazez