I am doing a little experiment with this right now myself. I have neon multicolored gravel in all but 1 tank right now. I have had the best luck with this ugly ass gravel, so I am going to try sand and see how it works out. I am using a typical off-white silica sand you get at menards with a bunch of agates scattered in it, a small piece of wood, and a fake plant with a blue background for color. I am going to see if there is any noticeable difference, because I am kind of tired of this ugly neon crap. I have seen many videos of amazingly bright, happy, and very colorful flowerhorn on white sand and I am hoping I can keep using it. I will def. let you know how it turns out. Also, I don't see why sand would be a problem for FH, other than it being light colored. You have to imagine that nearly all fresh water fish have a mostly sandy environment.

