What Is This Oily Film?

Discussion in 'Freshwater Beginners' started by Kat129, Apr 19, 2017.

  1. Kat129

    Kat129 Valued Member Member

    Hi everyone.

    After a failed attempt at fishkeeping a few years ago I am attempting to set up a new tank. Trying to do it properly this time so I end up with nice healthy fish.

    I have a 64l tank that I have started running a fishless cycle in. I am on day 3 with ammonia at 4ppm.

    Today I have noticed an oily film on the top of my tank. What is it and will it go away when my tank is further along on its cycle?

    My tank contains 3 pieces of wood (that have turned the water brown but that is ok) and 8 plants. No fish yet.

    I added Interpet Tapsafe when I added the water and Filterstart on days 1 and 3.

    Any advice gratefully received.

    Thank you
  2. Summer22

    Summer22 Valued Member Member

    I've seen people ask this very same question before and my tanks have it too. Someone said that it's just the oil from your fingers. Then someone else said it could have come from the new filter added if it wasn't rinsed or something. I choose to side with "oil from fingers". What ever it is, it is totally harmless, and for me, it has never gone away in the year I've kept fish.
  3. Punkin

    Punkin Well Known Member Member

    I've had that happen to me when I did not have enough surface agitation. If you increase the flow of your filter (depending on what kind you have), it should go away. Mine was just from oil in fish food, etc. The surface of the water should have some movement, the more the better, especially for oxygen exchange. And in turn, the more agitation, the less oil film you should see.

  4. Nanologist

    Nanologist Well Known Member Member

    I call it "bio-film". Just proteins and organic materials from the food, fish waste and what not. I had it in my tank as well and it started getting thick enough to where I was concerned about my Betta having to breathe through it, so I created a little scoop for my filter to direct the water coming out towards the surface to agitate it much more. Now it only collects in one corner where some of the plants slow down the water movement.
  5. Punkin

    Punkin Well Known Member Member

    Agree, I have a tiny corner behind the heater that doesn't move alot so there is a little triangle of film there, but the rest is moving. :)
  6. 2211Nighthawk

    2211Nighthawk Fishlore VIP Member

    Agreed. Get the surface water moving a bit more and it will go away.
  7. OP

    Kat129 Valued Member Member

    Thank you everyone. Is it still likely to be biofilm if I don't have any fish yet? Just gravel, wood and plants in my tank at the moment.
  8. Nanologist

    Nanologist Well Known Member Member

    Yeah, most likely. Can you get a pic?

    What are you using to cycle the tank?

    Any decomposing organic material will do it. It's from the wood, plants and the bacteria that's growing.

    Here's a great explanation:  
  9. Bodesca

    Bodesca New Member Member

    I hate having the biofilm. I make sure there is enough water movement to prevent it.
  10. OP

    Kat129 Valued Member Member

    Can't get the angle right to see the film on the water so this is the best pic I can get. Sorry.
    IMG_2193.JPG IMG_2192.JPG
  11. Nanologist

    Nanologist Well Known Member Member

    Yeah, that's biofilm for sure. Not much of a problem and means your tank is growing bacteria, which is great. Most people just don't like the sight of it, but also if it gets too thick it hinders oxygen/CO2 transfer to the water. Like we mentioned, just get more surface agitation from your filter or a powerhead and it won't be able to collect.
  12. Punkin

    Punkin Well Known Member Member

    Very nice looking tank, too. :)
  13. Nanologist

    Nanologist Well Known Member Member

    Agreed! Can't wait for it to cycle and get some fish in it. Looking forward to more pics in the future.
  14. OP

    Kat129 Valued Member Member

    Thank you. I was given some mature fiter media from a friend yesterday so hoping it won't take too much longer to seed and cycle. Just need to work out what fish to put in it now!

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