I thought I had a better one… but at the very bottom you can see the top of the sand…
I use Leslie’s Brand Pool Filter Sand (Pool Store Chain) in almost all of my tanks. I’ve found it is larger grained than most PFS’s and therefore stays on the bottom of the tank and out of my filters quite well.
I have two BGKs (in different tanks) and both have done fine with this sand, one of them for over 5 years, the other for a year or so. I don’t know of any way it could be bad for them…
Yep, I keep my bgk with white sand and have never noticed any problems. I don't see how it could either, as when it is dark (which is when they are active), you can't tell the difference between the white and black sand anyways.