Oily Film

[Myanth]

I got the same on my 10 gallon nano. I just skimmed the surface with a cup to get rid of the film. Hold the whole cup under the water so just the meniscus skims in. Let it flow into the cup as little as possible. You will see the gross looking and bad smelling skim accumulating in the bottom of the cup. Don't let it overflow or you start over again. Worked for me. Helps to turn off any surface agitation a few minutes before to let the skim join together.

Good luck
Mike