It depends what fish you have and what color is better for them. If you have fish like geos or bichirs, they benefit from having sand. Geos need sand to sift for food. I bought geos from a guy who had them in a bare bottom tank and it just didn't look right because they're earth eaters and they didn't have any earth to eat. Personally, I like black sand (3M Quartz) but when I had it in a tank full of Indonesian Tiger Datnoids, it made all of them turn black. Changing substrate color fixed that. I would use either 3M black quartz sand or pool filter sand from Leslie's pool supply, both look very nice.