Oily looking film

[big.]

Ever since I stopped all surface agitation of my 20 gallon high tank, there has been this weird looking oily film on the surface. The tank has been set up for about 7 months and is cycled. I tested the parameters and they are perfect. I have done 2 50% water changes over the past 3 days. Any thoughts on what this is and how to get rid of it?

 

[P220]

It's just a natural film; could either be a protein bio-film (if it stays intact when you stick your finger in it) or Eisen Bacteria film (if it breaks apart more easily). Adding your surface agitation back should clear either up

 

[big.]

Is it harmful in any way?

 

[P220]

It can lead to a build up of CO2 in your tank, since the film will hinder the CO2 to O2 diffusion at the surface.

 

[gilpi]

At one time or another I always had some film on my tanks on the surface as well, doesn't mean it's a good thing but it does not worry me. I was obsessed by it at first, after multiple water changes the film would still be there! Even with lots of surface movement I still see it so I just don't worry about it anymore.

 

[big.]

Thank you for the responses, I will leave it alone and if the fish start to gasp at the surface I will turn back on the air stone.

 

[Ian086]

Thank you for the responses, I will leave it alone and if the fish start to gasp at the surface I will turn back on the air stone.

If your worried, you can get an Eheim Skim to keep the surface clear....

 

[gilpi]

Your fish are not going to gasp for air from the film, the film is not a sealer on the surface keeping co2 from getting into your tank. As long as your water is in good condition meaning regular water changes and good filtration you'll be fine.

 

[konmanos]

OK, I have found that I also had oily residue on my sump tank. The main tank was recently containing oily residue and no matter how much surface agitation.... Still oily.. Today I decided to go a little further than just the weekly water change.. I changed the filter sock and instantly the oily surface was GONE.. I therefore can only recommend that you maintain a strict habit of cleaning your filters and whatever keeps your water clean and I am positive that your oily residue will be a thing of the past.. I have two tanks and I find that the tank I have at work, that does not get looked after as carefully as the one at home is the one that starts to have issues..


Tank - 1 - OFFICE

Aquascape - initial setup March 2014 and then rescape August 2014

CADE Tank 800 x 800 x 600 - 320 litre

Sump filtration - Long noodles, 3 Layers Filter Pads. Carbon

UVIEW sterilizer

CO2 with inline reactor

ADA fertilising

ADA soil setup

RAZOR LED lighting

Twinstar


Tank - 2 - HOME

Juwel 120 litre tank - setup Dec - 2010

Fluval 406, cannister



Inline reactor c02, compressed

LED lighting