Surface Water Contamination

[Gooner]

I am starting to notice a build of tiny particals on the surface of the water towards the opposite end of the tank from the filter outlet. Someone has suggested it could be dust,
I have a Jewel Rekord 120 with all the standard hardware including the hood. It is only opened at feed time and cleaning time. If I crank up the bubble bar to its max they dissapear within a couple of hours and it is hard to tell if they are floating in the water as there is a lot of tiny air bubbles.

Is this normal, or could there be something contaminating the water.

All fish are fine and not showing any signs of distress.

 

[ox5477]

I think it could be just protein from your fish food. I've heard other people talk of this and I guess one of the best ways to solve it is to run a peice of paper towel over the surface and it collect the "slime" of protein.