You can put them in the sand bed on a rock, they'll just grow their skeleton outwards from there. Just make sure you don't let them get covered up by a goby or some other critter messing around in the sand.
I'd say these guys are extra adaptable.....they do not need to be down low, or in low light, or on the sand bed, or in low flow. They're sort of a lagoon coral....so they can tolerate quite a bit that some corals can't. I've even seen someone (in a book maybe) describe them in the wild as "the coral that grows where others don't". LOL
A lagoon can have either very bright light since typically they are shallow, or very lowlight due to particulates in the water. Flow can be highly variable too.
Put him where you'd like him – just don't let them be near another coral that could attack. My Hydnophora ate my first favia the night I brought the favia home. "Oh wow...what are all those strings all over it??" ;Bucktooth Nothing left in the morning but skeleton.
This overhead pic can give you an idea of the proximity in the wild. The inside probably fills and drains with the tides and only gets really shaken up during storms. That's not a guaranteed calm under the surface though as the tide can get channeled which can create some serious flow velocity on a localized basis. Depth inside the lagoon can be highly variable too....near the reef is obviously shallow, but the middle can be very deep – to there's potential for a wide gradient of possibilities for all the corals found in this environment.
Notice there are lots of species and some are more cosmopolitan and can be found just about anywhere corals grow, but lots seem to compete well in environments like this. Click though the list (which is from JEN Veron's Corals of the World website.) and check em out!