I guess it's not really a problem, it just looks nasty. The surface of my tank is constantly covered in a nasty layer of oily stuff. I did a water change and made sure to skim a lot of that crud off about three days ago, and now it's back. I can get rid of it by taking out my overflow tube to create a waterfall into the overflow, but that's loud and annoying and then the oil just comes back the next day.

I remember reading/seeing some product that was suppose to be used to get rid of this, but I don't know if it's safe or actually works (or even what it's called...).

Anyone know what causes this? It's driving me crazy :(

Try pointing a power head or return line at the surface to break it up. You want that scum to go down your overflow so it can be skimmed out.

I agree with PSH, this is what I do. I have read of people skimming it off with a paper towel but I've never tried it.

Haha, manually skimming it off with a paper towel. That sounds like fun.

I'll try the powerheads. If not, then I guess I get to deal with listening to the waterfall :(

I used to have this problem all the time when I had a HOB overflow. I tried powerheads and they work. The thing that worked even better was when I added a second U-tube to the overflow. Seems that the extra siphon helped.

Food is what causes it.. that and anything on your hands/arms that you put into the water....

Do you have a sump? Overflow system? Do you use an overflow box? Just adding an overflow box, to an existing overflow will increase the ammount of surface skimming that happens.

Dave