hmm I see what track your going down and i know exactly what you mean people see them in pet stores on sand and think that they must be in desert areas surrounded by sand but they are on the out skirts where its hot but not so sandy but if people are so worried about impaction it means that surely they don't have total faith in the care they're providing because im with you on the side of this argument that they should be fine as long as they are kept well with everything in the right amounts and i use naturalistic sand myself just for aesthetics but i know what you mean by the calci sand my local exotics has a new owner who now only stocks that crappy red calci sand and the blue and green gravel that's more pebbles than thick sand i was so annoyed when i found it out as i now have to order it of the internet