It looks ok I guess. I have white sand in one of my tanks with marbles...been contemplating trying at least a couple of the blackies on the white. I guess I will wait for updates with yours and if I like it, I may go ahead and do it. But as of now, I am more a fan of the black and natural looking sands.
I wish I went with bare bottom in my ray tank and painted it black like you did. My rays love the sand but I never get to appreciate the colors of my rays