I have some algae stuck on the silicone in my tank. Ive tried many things which include, a toothbrush, mr clean magic eraser, velcro, and a sponge. Nothing got rid of the algae on the silicone and it looks nasty.
I actually think the black silicone looks nice and clean too. I saw a tank one time that almost looked like the glass had a tint also.. but it was clear.. weird.. with black silicone..I've left it there; scrub too hard and silicone starts coming off with the algae so I don't want to take chances. I actually have one tank with black silicone, and while not to everyone's liking, I think it's kinda sharp.