you can buy black egg crate off line. I wouldn't paint it, and black would absorb light anyway.
I have white egg crate over my tank and there is a noticable difference between when its on and off the tank already... so putting black there would probably block it more.
I have white egg crate over my tank and there is a noticable difference between when its on and off the tank already... so putting black there would probably block it more.