Oil Slick, On Water Surface?

[Plecc]

Hi all,

Ive been having a bit of trouble with one of my small tanks.
The tank is planted with a very thin gravel substrate and has rocks, shells and bog wood for decoration.
At the moment the tank is full of juvenile BN plecos a few platty and a lone cherry shrimp
The tank has been very stable for a year or two with the only problem being a very persistent slow growing fluffy black algae.
But over the last three or four months a thin oil like slick has developed on the surface, the water is well oxygenated and the surface is agitated.
For water treatment I'm using Seachem Prime, and as far as i can tell nothing has happened that could have caused this, oh and this tank has never been treated with any form of medication.
So if anyone has a clue what could be causing this?
please let me know.

Thx.

 

[tenohfive]

If it's the multicoloured petrol slick type thing then it's probably just oils from the fish food (and therefore harmless.)

 

[Plecc]

Yep, think you may be right!
defiantly doesn't seem to bother the fish at all.
but i do feed the same food to other tanks with no problems.
can you think of a way i could remove it? It makes the tank look messy.

 

[doresy]

Yep, think you may be right!
defiantly doesn't seem to bother the fish at all.
but i do feed the same food to other tanks with no problems.
can you think of a way i could remove it? It makes the tank look messy.

You could try getting one of those paper hand towels (or best quality kitchen roll) that they use in wash-room. Open it out and lay it on the surface for a couple of seconds then lift it out. (Don't use tissue though)

 

[Danbarb]

You could try getting a small container like a small bucket (make sure it's cleaned first with some tank water properly) and lean it at 20 degrees or so in the tank and lift out which I think would get rid of the film. Obviously best to do this when you do your next water change, as you can just replace the water.

 

[juliedavis]

Yep, think you may be right!
defiantly doesn't seem to bother the fish at all.
but i do feed the same food to other tanks with no problems.
can you think of a way i could remove it? It makes the tank look messy.

you could try a soup ladle too and skim the oil out like you would for soup! i'm an ex chef no reason why it wouldn't work, but kitchen towel would work too i think.

 

[mbsqw1d]

do you have anything disturbing the surface of the water (i.e. your filter outlet)?

 

[Danbarb]

Ladel sounds good but kitchen towel no. If you've washed the kitchen towel in a washing detergent (even though it has dried out), then I wouldn't advise using that in contact with the water - just in case. Could contaminate the water.

 

[matuk]

its also oils from your hands when ever you put your hand in the tank to clean it etc

 

[juliedavis]

Ladel sounds good but kitchen towel no. If you've washed the kitchen towel in a washing detergent (even though it has dried out), then I wouldn't advise using that in contact with the water - just in case. Could contaminate the water.

sorry i wasn't clear meant the paper type stuff as mentioned previously

 

[JoshuaA]

As far as I know it is the proteins from the food, it is those oils that float on the surface of the tank.

The best way of countering this I have found is just removing all uneaten food quickly after being fed. As well as using an undersized hose perhaps a 1cm diameter hose and using it as a siphon however having half of it above the water surface, it will quickly suck in most water on the surface + oils.

There is concern that this can prevent oxygen transfer into the water if left to build up enough and there isn't enough surface agitation.