What's this sludgy stuff

[Ponch]

While doing a 50% water change I noticed inside the lift tube of my sponge filter... around the opening where the airline tube inserts into the lift tube.







Sorry for fuzzy pics- best I can do with the iPhone. Is this beneficial bacteria or just tank sludge?

When I filled the tank and turned everything back on it blew out of the tube and into the tank-everywhere. Yuck.

 

[LyndaB]

You can clean off any part of your filter housing, including the tubes, without ruining your beneficial bacteria. The only thing you don't want to mess with are any sponges or biomedia within the filter itself. Every few months or so, I take the filter apart and rinse off every little thing, except for the media.