# Thin film stuff from canister filter output tube



## htjunkie (Jul 20, 2012)

I've switched to a canister filter now for about 3 weeks, running the old media in the canister. Water test has been perfect so far, and water in crystal clear.

One thing that I don't quite understand is, whenever I need to turn off the canister filter (i.e. feeding time), when I turn the water flow back on, I see pieces of thin semi transparent films just getting into the tank. I can only assume it's coming from the filter? When I have water flowing, I don't seem to see this. Is this some kinda buildups inside the outflow tube?

Do I need to worry about it? I see my fish they just eat the thing. This is a freshwater setup.

Much appreciate your help.


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## Darkblade48 (Jan 28, 2008)

It is just some harmless biofilm gunk (or even algae) that accumulates within the filter tubing.


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## characinfan (Dec 24, 2008)

It is harmless for now, but it does build up over time. Eventually it will reduce the water flow. At some point, you are going to have to clean the tubing with a "snake."

The biofilm is harmless to fish otherwise.


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