Oily Film on water

C

chrisfromnl

AC Members
Feb 20, 2006
117
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St. John's, Newfoundland, Canada
It looks like there is an oily film on top of my water in the corner farthest from my filter. It kind of looks like when you spill gasoline on a water puddle, with all the rainbow colors. It's a new tank/filter and I have the filter from my old tank installed in it temporarily for bacteria reasons.
Is it from the new tank? Filter? rocks? Or is it something from my Dempsey?
Just change the water I guess would be the solution?
 
did you clean out the tank before filling it? Could be grease or chemicals from the manufacturing of the components/tank.
 
did the cloth ever have detergents or something on it?
 
This definitely only appeared tonight. I just changed like half the water, and it's still there. I just put the older filter with the bubbler on it back in as well, and I can still see it. When I touch the water with my finger, the oily substance parts. I'm scared for Jack :(
 
The oily film you are witnessing is a mix of protiens and dissolved organic compounds. This is a natural film that forms on top of the water. It is why many canister filters use surface extractors for the water intake pipe.

Activated Carbon and aeration with airstones will help dissapate this film. Make sure you are doing at least a 25% water change weekly to help breakdown the buildup of D.O.C.'s
 
Ok. I fed him today but he didn't eat it all (floating pellets) I guess it came off the one or two that were left floating?
He's in the corner of the tank hiding behind a plant now. He's not moving much, I assumed the worst. Whew.
I'll keep you posted.
 
like mr. firemouth said, it's mainly dissolved organic compounds.
but there's more to add.
lemme break it down.

the canister filter normally fails to break the surface tension of water all the way across the surface in a long-ish tank, yeah? yeah. so what ends up happening is little invisible-to-the-naked-eye co2 bubbles float upwards (as bubbles do) towards the surface of the water. along the way, these bubbles collect teensy microscopic organic compounds and these compounds stick to the bubbles. much like the way a protein skimmer works on a saltwater tank.
so these bubbles get to the surface and try to escape, but alas! the surface tension on the water is far too great for the bubbles to break through. so they just chill out right underneath the surface of the water and create that lovely film you see.
the end.
 
you can turn off any surface aeration you do have, take some clean paper towel and lay it down flat on your water and it will take a lot of it off; but this doesn't obviously address the reason for the build up.

long term look at creating more surface aearation to stop it building up.
 
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