Funct. of foam in overflow?

[Texas Reefer]

So just now I look in my overflow, hunting for my starry blenny (who is in there! Yay), and I realize how nasty it is! Something red (algae or Cyano?), and a circular foam thing that wraps around a pipe. Please feel free to comment on anything you see in the pic, but what is the foam's function? It's pretty nasty, can I soak it in some vinegar and replace it? Do I even need it? I'm planning to clean the tank today and empty the overflow, if possible, clean the overflow and get my blenny. Thanks for the help!

 

[Texas Reefer]

Here's the pic!

 

[Vpham]

I got that in mine too. IMO, that's bacteria slimming when they grow into a colony.
I would leave it alone if it doesn't restrict water flow.

 

[Harrisd503]

Depending on where the foam is, it can be used to catch run away fish or larger particles. It does need to be cleaned on the regular or it will become a block of decaying matter. I don't think many people use it, better to keep everything moving throughout your filtration.

 

[Texas Reefer]

I guess I'll clean the foam and come up with a way to cover the overflow to block out light. That way algae can't grow, but can red bacteria grow without light?

 

[NanaReefer]

That red is cyano so there's bacteria in there. Personally I'd be cleaning it out, on a regularity. Plus put a cover on your overflow. Save fish & keep light out