Frage Rust looking color on aluminum T-slot

Aluminum issue:


Dear all, while using the milling bath, some water leaked. (My package did not include the necessary fittings to seal off the whole and connect a tube, so I temporarily tried using duct tape).

when I saw the leak and removed the milling bath, I noticed some of this rust looking material on my T-slot table. Does anyone know what that is and how to get it off? It looks completely burned into the surface.

Thank you!
Arjun

Found the answer to my own question: apparently if water and carbon fiber dust sit together on aluminum for too long (hours), because the carbon fiber is a conductive material, it can cause galvanic corrosion of the aluminum. It is a harmless thin layer of a brown looking color on the aluminum.