filmy substance, anyone had this before?

[V10]

I noticed the other day that there is a strange filmy substance floating on top of my water, looks kinda like an oil slick and I've never seen this before. Does anyone recognize it?

Tank is about 7 or 8 months old, I recently experimented with a dose of a tetra product designed to kill algae as I have a bad case of BGA, but it appears a couple weeks after using that product so I'm not sure that is the cause. I talked to my wife, she has not used any cleaners or aerosols in the area of the tank. It does not seem to bother the fish at all.

Do eheim pro II's have any kind of light oil in them that could lurch out?

*edit* filmy might not be a good word to describe it, it does not have any texture, it's very similar to gasoline/oil floating in a mud puddle.

[rich311k]

It happens, could be from the algaecide or from food or whatever else you may add to the tank. You can soak it up by floating a paper towel on the top of the tank. A bubble stone to break up the surface of the tank water will disperse it quickly. Nothing to worry about.

[Zagz]

I agree with rich. I get it on my tanks sometimes. I don't worry about it. I have bubblers on all my tanks.

[An t-iasg]

I've had this film before too and agree with Rich and Anne on how to treat it. I also had it when my tank was newly set up. It seems to have vanished now. I moved my filter output to better agitate the surface of the water and the film went away. My water surface ripples but isn't fast-moving or rough.

[QTOFFER]

I've noticed this film sometimes too.
It's most likely fat leaching from prepared fish food. I find it to be pretty harmless - eventually, it goes away on its own.

[triazole]

it comes in my tank when i use frozen bloodworms. nothing to worry about.

[frostby]

I had the stuff as soon as I added CO2, and stopped my surface aggitation. Suddenly for no change of tank maintenance, the stuff has quit building up, and now its barely noticeable. My tank just hit it's 8 month birthday. At one point at the 6 month mark, it was so bad I could literally 'peel' it across the water with a finger

[sabbott1877]

I love when I am about to ask a question, or am pondering something about my tanks when suddenly, there is the answer!

I have seen the same thing on the two of my tanks with less surface agitation, it hasn't seemed to hurt anything, and now, I guess I don't have to worry about it