I have had a few of them over the years....... mine always accepted sinking pellet type foods. Good luck with him....... they def sift alot of sand. It kind of made a bit of a mess, but was cool to watch. Keep an eye on if you have any small frags on the sand bed, there is a good chance they will end up getting buried by the sand these guys move around.
My last one got crushed by it undermining a rock in my DT.