Easy question to answer. NONE. Calci-sand or any calcium based sands are notoriously bad for reptiles. Crushed walnut shells is also bad. The main reason they are not recommended is they greatly increase the chance of impaction in dragons, especially young dragons. In the case of crushed walnut shells, these can also damage the internal lining of the intestines.
Calcium sand is much too coarse to digest so it is not a benefit at all to the dragon. The fact it is made out of calcium also has the tendency to neutralize stomach acids, so if too much gets into the stomach (stuck on food, swollowed after dragon's lick things in their cage etc) it can make digestion difficult. It also tends to clump up as well, making blockages more likely.
For juveniles at least 10" in length snout to tail and older dragons, you can use washed sifted children's playsand. Though there is still a chance this can cause blockages, it is not as high as with calcium based sands. You can buy this at Walmart or most home builder supply stores for about $5 per 50 pounds.
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PHLdyPayne