Nasty Black film

[cdawson]

I've got a really nasty black film in my planted tanks filter. If I had a dig. Camera I'd post pictures as it should be seen to believe. Anybody have any idea what this may be? Water quality is perfect, this really concerns me here.

[Cearbhaill]

What type of filter and how/how often is it cleaned? Where is the black gunk- in the media? In the tubing?
Smear some of it on a white cloth to determine if it is truly black or maybe a very dark green or very dark brown.

What are you feeding? Sometimes food gets sucked up before it gets eaten and the color of that would affect the filter media as well.

[cdawson]

Food isn't getting sucked up the filter, I feed on the opposite side of the tank and it gets eaten before it gets that far. Anyway, my filter is a tetratec pf300(I know I hate tetra after they did that show, but I bought it before the show). The slime is in the media, it looks almost like oil slick.

[OrionGirl]

Is it actually slimy textured? Sounds like cyano bacteria to me. Pretty common. It likely has an unpleasant green, earthy smell as well. Manual removal will help, treating with an antibiotic will kill it. If it is just in the filter, remove the filter from the tank and clean it completely out. Disturbing it into the tank will cause it to spread--probably into low light areas.

While not pleasant, it really isn't a bad problem in small doses. I have a large colony that grows in the substrate. It never grows anywhere else in that tank, though, so I just leave it alone. In another, lower light tank, it will form a scum on top of the water in the floating plants. I sweep it off and am seriously considering using the antibiotic treatment--have to remove the newts first--because when it has access to air it really stinks.