Weird 'rust' on my live rock?

[Jameyh]

Anyone know what the heck this is? I have been fighting and fighting an algae problem for a year now....decided to pull out alot of my old gulf rock.....under most of the rock were these 'rust-like' cracks and fissures...Anyone have any idea?? Sulfur of some kind?

thanks
Jamey

 

[jumpincactus]

Looks to me you have a low quality rock that was probably set in the ocean for seeding and resale as quality live rock. It looks like it contains some metals and it is corroding in the salt water......... Just a guess.

 

[RobbyG]

Seen the same thing on rock that has been used as landfill to make piersl. It's High Iron content land based rock. I would dump all of it if you can.

 

[Jameyh]

It is TampBay Saltwater rock that I got in the early 90s. I just kept letting it dry out and reusing it over the years in my tanks....When the rock was new, on my first tank, things were great....but ever since then, things have been crappy!

thanks
Jamey