No, it's not bits of food. It's mould growing on the inside of the lid, but mostly around the filter insert on my filter. Really looks like clouds, not little chunks here and there, but billowing clouds.
You might want to take out the insert or parts of the filter and clean it manually with hot water and a scrubby pad. Clean off the inside of the tank with a scrubby pad too, and net every bit of it out that you can.
I've never had anything like that before myself, so I really can't tell you what exactly it is. Almost sounds like something that occurs on a fish's slime coat when it's sick. If it was green I'd tell you it was green hair algea. Not sure there. If you have a knowledgeable lfs near you, give them a call and see if they could identify just what it is you've got going on. Good luck resolving the matter.~Angela