I recommend not doing it!
Keep the bare bottom.
I have alway done a DSB but I never will again. To much work keeping it "alive". You have to have a bunch of worms, snails, stars.... or you get "dead" spots. dead spots cause smell.
How thick of sand are we talking anyway?
My next setup will have a thin sand layer, about 1 inch, because I do not like the look of bare bottom and I do not want the trouble of a DSB.
Also, a DSB can crash.