The high desert sand is sand from the Great Salt Lake. There are articles on the net where it has been tested by Riddle and the likes back when New Castle play sand was widely available. The Salt lake sand was pretty high in Aragonite and Calcite, with higher levels of phosphate than New Castle play sand. Also there was a little silica, but not alarming levels. New Castle play sand is no longer available. It came form a single permit holding company in Bermuda, which now sells it as aragonite and only sells it to the distributers who sell it as reef substrates. Unless you have sand digging gobies and wrasses the Salt Lake sand is fine if it is available cheap. However, the silica sand irritates the gills of sand digging gobies and wrasses. Under a microscope silica sand looks just like small shards of glass. Aragonite will not dissolve in shallow sand beds because the beds at a shallow level have the same pH as the reef tanks water. Therfore, without a deep sand bed there is no real reason to use aragonite sands, as it does nothing to supply trace elements or calcium when it does not dissolve. It requires an oxygen free environment in a reef tank to have a low enough pH for aragonite to dissolve. Therefore the only advantage to having aragonite with a shallow sand bed is that it can be purchased in fine grain sizes that do not trap detritus like coarse crushed coral. Calcite (crushed coral, will not ever dissolve in a reef tank no matter whether their is a deep sand bed or not as it requires an even lower pH than aragonite to dissolve. Sorry if I burst the contentment bubbles of once happy aragonite purchasers.
