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I have noticed and have always wondered why there is a oily substance on the highest level of water in the tank. It only appears at the top if i look at it at an angle with the lights on from the bottom. Its a filmy rainbow substance that has me confused? Is it my quality or does this happen to everyone?

20 GALLON LONG CURRENTLY EMPTY ~~~~ 10 GALLON W/ STRIPPED CONVICT

This may be soap from a bucket that you use or oils from your hands, anything. I had this one time when I put hand cream on and then but my hands in the tank. Take a cup and skim off the top. Make sure that non of your fish "stuff" comes in contact with soaps or oils.
Good luck finding what is doing this.

Well its either going to be trace pollutants or fats from livefoods and oily food. Do you have spraybars or aerators running so that surface films have a chance of going back into solution and being picked up by the filter? Might be a simple maintenance issue, either way, try skimming it off with a jug or a cup asap. You dont want pollutants or protien and fat scum thickening the surface layer and blocking off oxygen.

If you think its household chemical scum, cup it off, do a decent sized partial water change and run carbon.

If its a flow related issue, run aerators, spraybars and filter outlets in a way that disturbs the water surface asap.

what size tank, and what type of filter is on it? I've noticed also on my smaller tank thatif the filter is too low or running slowly that I get what sounds like the same thing. Goes right away when I turn it up tho. When I turn it off like for a water change or cleaning the oily spot does not reappear so I assume it was related.

Its a 10 gallon tank with a Whisper 10 gallon filter on it.

20 GALLON LONG CURRENTLY EMPTY ~~~~ 10 GALLON W/ STRIPPED CONVICT

A Whisper and you see some film? That's unexpected as Whispers are normally great filters. I don't have a Whisper 10, but on my Whisper 40 there's this thing that allows me to turn down the flow for feeding; if the Whisper 10 has it, make sure that you are allowing the flow to be at its highest.

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The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.

Hi Peter,
This is a perfectly normal situation and is most usually
found when the fish are fed the more inexpensive foods.
Read the labels on the fish foods. What you are seeing
is the result of the fish oils and fats that are in the
food. This, combined with household dust, smoke and
grease from food preparation and cigarettes and pipes,
all combine to form a scum on the surface of the tank.

Longhairedgit is correct.

A good tight fitting cover, will prevent the external
pollutants from hitting the surface. You can eliminate
it by laying a paper towel on the surface allowing it to
wet the towel and then removing the towel. Doing it a
few times will pick up the pollutants. Using an air stone
will cause the scum to break up and sink to the surface
of the gravel where you can siphon it off. Also a good
filter that agitates the surface will prevent the scum
from coating the entire surface. Instead, the bubbles
of the film (from the surface agitation) will capture
dust particles and settle to the bottom.

Changing fish foods will also eliminate most of the oils
and proteins.

Frank

-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Frank,
I scimmed the surface of the tank and it went away. I am feeding my fish with Wardley products. Cichlid foods to be more precise, I am not sure what else it is called off the top of my head but i think its called Hikari? I also throw that in sometimes too, are these cheap foods? Also i think it is due to my overfeeding especially with the pellets that he dosent eat, they just float around..so thanks man, great advice..i will try the papertowel thing.

20 GALLON LONG CURRENTLY EMPTY ~~~~ 10 GALLON W/ STRIPPED CONVICT

Hi,
Read the various labels on the foods in the LFS.
Those with oils in them are the guilty parties.

Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Wardley is rather on the cheap end. Hikari, on the other hand, isn't cheap, in fact it's one of the best brands. That said, I don't see any film, and I have used both brands in the past.

--------------------------------------------
The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.

The whisper is one of those long cylindrical things thet hang down into the tank? That's exactly the setup that I experienced the film. As soon as I replaced the filter it went away.

Its not a cylindrical filter. Uhh I looked on the wardley label and it has many things that a hikari product dosent I switched and I see gradual improvements..thanks guys!

20 GALLON LONG CURRENTLY EMPTY ~~~~ 10 GALLON W/ STRIPPED CONVICT