Whats this in my water?

What's this in my water? It looks almost like an oil spill does on pavement. I do regular water changes, 20% weekly. Could it be copper? Please help.

 

Could be fish oil. Probably means you need to break surface tension so that the skimmer can pick it up. You'll get better O2 exchange as well.

 

Is it on the surface? If so then +1 on whippy... Or if all your water just has a Kellie tinge to it, then it's gebelstoff- a build up of organic matter in the water. This is also cleare by skimming and a change of your activated carbon filter

 

I had an oil look on the top of my tank as well, so I added another power head, pointing up at the surface to cause a lot of movement. Worked!

 

Here's a picture of it.

 

Well the picture I just tried to add didn't show up.

But is this harmful to my tank? I don't have a skimmer yet. I plan to get one when I move in early June, as I will have a bigger tank then. I also have no power heads yet. I only have one fish and a few inverts in my tank.

 

and yes, it is only on the surface. My tank water appears clear except for the surface. Will it hurt to wait until I move to get these things?

 

It's hard to say. There's a good chance it's preventing gas exchange at the surface which can cause low pH and low DO (Dissolved Oxygen)

 

Float a piece of newspaper or a couple paper towels on the surface every once in awhile and it will remove it. No big deal. Foods have fatty acids in them.

 

That does it? Good Idea. Though probably shouldn't use newspaper, as it could release ink into the tank.