Black looking stuff on my return lines in the overflow box
 

Hello, when I was having someone help me to try and get one of my clown fish out of my overflow box. We notice that there is some black looking stuff all over where my return lines connect to the overflow box. The overflow box is in the center of my 230 gallon tank. We just took the black stuff off and threw it in the garbage. It had the same consistency as mud. I was wondering if anybody knows what it could be. Also none of my lines within the overflow box are glued together. Is it a good idea to glue them together?

Thank you
Rick

It's probably algae. I have a few different varieties of algae in my overflow box along with that real slimy,almost black colored crap. Nothing to worry about. If your fittings are threaded then they're fine. If they're push-fit then they should be glued.

Thank you for the input. My fittings are not threaded so I guess I will glue them. I have to take the majority of the water out of the overflow box to get my black clown fish out of there anyhow.

Rick