# Bacteria, oil, or..?



## dabrybry (Jun 27, 2010)

Hey ya'll. Have this nasty surface film that seems to accumulate over the week before water changes. 








Does this look like some sort of bacterial bloom to you? Or maybe phenol oil build up? If it IS a bacterial bloom, would I be best just leaving it and letting it do it's thing to let it cycle away and go on it's own? Tanks been set up for almost 3 months now by the way :/

Thanks in advance for any comments/help/suggestions!

-B


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## Big_Fish (Mar 10, 2010)

biofilm ... it really doesn't hurt anything.
you can agitate the surface a bit with an airstone, if it's really unsightly you can float a paper towel on top of the water... but it'll come back over the next couple days.
some folks seem to get this more than others, and MAY indicate either too high a bioload, too much fish food, or a critter that went belly up but not noticed.


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## dabrybry (Jun 27, 2010)

And what exactly is bio film though? There has to be a way to rid the aquarium of it. I really don't think it's the bio load, and I haven't had any fish die. The tank is heavily planted and a 42g with only 18 green neons and 3 sae's.

Here's a pic of the tank a while ago cleaned up, but still when it was having the same biofilm problem


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## JustLikeAPill (Oct 9, 2006)

It's a film of life : P Bacteria, tardigrades, all kind of neat stuff that establish on the surface because of proteins that have a hydrophobic and hydrophilic end (so one side wants to attach to the air and so it builds up on the surface. That creates a substrate for the harmless critters to live on, but this layer can inhibit gas exchange and is gross looking. 

You need more surface flow to prevent that, or a skimmer, or a lily pipe outflow.


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