The calcium particles used to make up calci sand are too large to be readily dissolved in the gut. This type of sand can form clumps in the gut leading to impaction. The mass of calcium can also act as an antacid and reduce the lizards ability to properly digest its food. In my opinion, regular sand is safer. I've kept alligator lizards on alfalfa pellets successfully, but had the shedding issues that plagued FunkyRes with juvies maintained in this fashion. I've kept all of mine on orchid / repti bark for the last several years without issues. You can read an interesting article on calci sand type substrates here: http://www.pythons.com/calcium.html

-Alice