Well I have lost two scorpions so far for no reason, that were both on this substrate. In fact they were the only two I've lost. Both developed mycosis but neighboring scorpions of the same species did not. One was Mesaensis, the other an Australis. Both were kept at 30% humidity. At least that was the humidity right outside the enclosure. I am going to throw a RH meter in there to see what is really going on. My prego Australis is right next door and she seems plenty healthy but is on high dollar sand.